Your written English is not very good and you obviously lack self-confidence. Remedy the first and get over the second. If all else fails you might want to bleach your hair and wear lenses. Being rejected twice does not mean you´re doing anything wrong, just that someone else did it better.
If you need a fail-proof gimmick just buy a kitten and take it to class.

Best of luck,

And yeah, my English isn´t perfect either, but I´m not a teacher.

are you white? if not then thats why.

If you are then you probably didn't smile enough or seem friendly enough. perhaps you sounded too italian.

Its often the students in the demo classes that have a big say and the 'entertainment' factor goes a lot further than teaching ability or knowledge of the language.

You don't really need to do anything other than ask them a few questions and grin stupidly.

third time lucky?

Don't worry about it too much. The main thing is to make the kids laugh and have a good time in an English environment. With adults it's kind of the same but you got to put a lot on their side of the court so they do most of the speaking in the activities you've prepped. Demo's can be frustrating due to the fact the students attending are the Chinese staff or existing students who aren't used to your style of teaching. Don't let it get you down, there's plenty of teaching gigs out there.

you have to be joking about the russian.
thats sounds so crazy I almost believed it.

There you have it. The China market, from my observation, is the business of entertainment. Too many places here offer English learning services and way too many students are required or want to learn it for status advancement. This means that you get a market full of people who would be unemployable 'teachers' in their own countries but are native English speakers. There are good teachers here, without a doubt, but most are delusional or overtly and psychotically protective of their China turf.

In other places, they will normally hire the best person for the job regardless racial background or gender. However, in China, it seems like the only thing that matters is how much your students prefer you and believe they will learn. You have countries all around Asia where English is spoken and some where English is the first language. Why recruit a western speaker? Because this is the business of entertainment and false perception but not acutally learning.

Being born a native English speaker does not qualify you to teach English. However, you can overcome the demo class by understanding that you have all the face value tools to be an English teacher, and I doubt if some of your employers or students will even know that English isn't spoken as often as Italian in Italy...You're European! Point this out every time you're ever challenged in your demo class. My only warning to you is don't get sucked into believing that you're an actual teacher, because if it was just about grammar then they would be recruiting Singaporeans.

Sorry OP. Yes, you are right Nomadz.
It was an exaggeration. But still, I disapprove of native speakers who are not professional in their teaching while claiming to be professional teachers. I know an Italian whose English is Chinglish at best and though he does have a degree in foreign languages, English was not one of the languages he studied. Yet he is an English teacher in China.

Stage fright?

Picture all the kids naked, that's what they usually say.

I think it is hardly about the quality of his (the Italian guy's) English. I have taught English here for a couple years now off and on, what I have learned is that there is a lot of native teachers with MA degress in education, yet they are a-holes that take themselves too seriously, so the kids hate them or find them boring (myself included at times). I think that the Italian guy's English is MUCH better than most of the kids I teach, so I don't see why that would be a problem.
I agree with the posters that say you just need to make it fun. I ususally open with a song, head-shoulders-knees-and-toes, then give them pics i googled the night before of say fruit and veggies. After they repeat the word a couple of times (do you like onions? Onions make me cry, but I love to eat bananas, what animal likes bananas, "Monkey!" Good.--- Like that.) you make 2 teams, so you need two of each pic. then write fruit on one side of the board, and veggies on the other. Describe, then say a fruit or veggie. Two kids have to run to the board, slap it on the right word and say "I like to eat carrots/apples/kiwis/green beans/oranges/mangoes/etc." the fastest kid gets a point for his team. Announce the scores frequently and say "whats going on gang? 4-5, you have four, they have five!" (teach numbers). The winning team gets stickers. One each. Dont let them choose, it'll take all f-ing day.
Another game, really easy and they love it is ABC. Line the kids up, the first one says A 2nd B and so on, if the kid f***s up- stumbles, takes longer than 3 seconds after you point to them, or says the wrong letter, they have to sit down. They are out. If you get through the alphabet do 2 letters, AB, CD, DE, EF, then 3 ABC, DEF, and so on. The winner gets a big sticker because they are the best in the class, and I make the other kids clap for them.
Then have your closer, if you're happy and you know it, if you have never heard this song google it. But make it funny, you are an actor, you are a clown, you are the DUDE. If you're happy and you know it dance the funky chicken, if your happy and you know it do the twist, and remember, the last time you have to do the previous seven, which makes everyone laugh, oh we love so and so teacher so fun is what they are thinking because you left them feeling elated. I had to do this sh*t in classes with 20 kids who loved it, but their 40 parents all just sat there and watched me, as well as five other teachers from the school. Kind of humiliating at first, but realize, they start to really look forward to seeing you, they appreciate the fact that you humble yourself enough to act like a total dipshit.
sooooooooo,
1. Opener- song
2. Substance- vocab building game.
3. Closer-song.
always bring stickers, you can get em at yaxiu market for 2-3rmb/sheet, and this will make your job soooooo much easier, kids love that crap. I also use little erasers.
just try to relax and be fun, be a clown, be humble, be excited, be a guy that you would want to see again if you were a little kid.
Good luck man.

I think that if ESL teachers have previously been ESL students, they really have an advantage.

For the company that I am presently employed by, I was required to give a demo class. To make things more challenging, I wasn't giving the demo class to students but to people in suits who I discovered at the end of the class were principals, directors, and supervisors of various language training centers and schools. To add a democratic touch, they all rated me, added their comments and put the matter to a vote. I have never been voted into a school before but at least the vote was unanimous.
Almost all companies and schools I have contacted or been contacted by initially request a photo, CV, and photocopy of my diploma, certificates etc. I thought that was just standard procedure. The company I work for now also required a letter of referral from each previous school I worked for. But for that last request I just gave them contact numbers and names for my previous bosses and asked them to make the calls themselves.

im a Chinese girl,working at a private English centre as a teacher.you know,what the employer concern most is the practican ability,not your degree,qualification.Do preparation work well in adcance:
Prepare three kinds of forms of class for kids(prepare some pictures..),teenagers,adults(spoken English which most are intrested)
Dont't worry.you can be succeed!
Good luck!

Put a lot of energy into it and play games, make it interesting, break up many parts and hone it until perfect.

Neither is yours. And so am I.

I personally hate demo-classes and i think they're useless for measuring a teacher's ability to teach.

Being silly and "entertaining" won't get you far.
Be sure that you are clear and convinced about your aims and you will have good teacher presence.

I don't know about your accent.
Accents are normally not a problem unless you're going to teach phonetics for a specific English accent/dialect.

If the problem is that your employer wants you took appear white, then don't take the job. The job is not serious and you'll just find it frustrating to work there. Find a teaching job instead.