Etat des lieux, how difficult is it to "survive" them...

Agree with the others above. It depends massively on your relationship with the landlord. I've moved out of three rented properties over a period of 12 years. That's with a family of four. Never had a cent taken from the deposit. No professional cleaners, we cleaned ourselves, but we also looked after the places when we were there.

We were excellent tenants. We never once bothered our landlord. We paid our rent on time every month. We never violated our contract. The landlord violated the contract several times in the last 2 months of our tenancy and we tolerated it in the hope he would leave on good terms. The only "damage" was the parquet floor which had been badly polished before we moved in had deteriorated and fair enough the landlord charged us for re-varnishing. However, he also attempted to blame us for damages that his work men had caused whilst renovating the house with us still in it, the expert refused his demands. We left on very very bad terms as a result. I learned that you have to make your best judgement at the beginning if your landlord is going to be difficult at the end. We misjudged to our cost.

Same here, our landlord has repeatedly violated his contract but out of the interest of civility we have let it slide. We have had no problems with the guy really yet when we gave notice the attitude seemed to change.
We had an agent threaten us nearly immediately because we knew the contract better than he did, I know for a fact that when we where away the landlord had work done on our property without permission or giving any notice at all and still yesterday agents are showing people around and turning up unannounced.

I'll let that last one slide as it was a second visit for the guy and the sooner the house is off the market the better and we can get on with what we have to do and not worry about others.

I think we have been very reasonable as tenants, the only damage to the property is caused by the shoddy patch up jobs from before we moved in. Funny how a nice lick of paint hides all the problems. Still we will return this house in better condition than we got it and I fully expect to get hit up for all the work he knows about that he covered up and god knows what he will come up with for his precious garden.
I'd love to be proved wrong though, and remember you have to sign off on the deposit too before it gets released.