Not a lot of people but nearly everyone............
Indeed, the ol' departing deposit debacle... However, there are ways, as usual, to increase the odds of success in your favour.
Speaking from experience, I would advise anyone who really wants his deposit back, (i.e., most of us!!) to take the following steps when renting in LOS. Most Thais are, of course, good, honest people. Then again, because nowhere is perfect it still pays always to be vigilant. It might seem strange/over cautious to take the following steps, but I'll just say these steps I definitely know to work, & simply offer the following as
bona fide advice for others here. Make of it what you may:
1) Firstly, It helps alot if you are renting with a Thai partner, and particularly that she's there when you're onto the business end of your rental.
2) Regardless, when you are first shown the room always take a few minutes to film every room & bathroom with a camcorder. If there's a fridge/air con etc., check they're working. Pay particular attention to things like cracks in the bed-frame, tears in curtains or even bedsheets, any marks on the well or near doorways. - as these are the common ways they try to claim that if it weren't for your staying there, it'd be in perfect condition (yeah right!).
3) Tell them politely and with a smile (always best in Thaland) straight away if you find anything sub-par - including visible marks/cracks, rips in the curtains etc., on surfaces. They might well give you a quizzical look, and say "don't worry, mai bpen rai ka" but it'll send the message that you're not the type who takes pleasure in being fooled.
4) Always ask to see the electricity and water meter reading for yourself, once when you agree to take the room, once during approximately the middle of your time there and lastly when you're leavng - as this is another way that deposits are either withheld or significantly reduced. Take a quick snap on your cameraphone, each occasion, if you can. It's not at all unknown that if you don't check as advised, that you may be presented with an extremely (read "suspiciously) high bill for utilities - met with a shrug of their sholders when you challenge it, and the remark that "you must have had the air con & the tv on ALL the time..." If you didn't check the meters you'll not have a leg to stand on if there's any standoff over the charges, and if, eventually, officers are called.They simply present an alleged reading for when you arrived (which (A) for all you know was taken a year ago... & (B) word of Thai > word of farang) and show the meter on the day you're leaving, which is all you can see if you don't check, and simply charge you the difference. They might even be scribbled onto the tenancy contract that you sign, which if you didn't bother checking it against the numbers on the meters (and most wouldn't), means that you're trusting that the readings are correct. Not always wise, if you value your deposit's return...
5) Remind them around a week in advance that you'll be vacating soon, and would they please take steps to prepare your deposit's return for you then . I know someone who says it's best, if possible, to get your Thai partner to remind them - as, frankly, he claims not only (& with all respect to any excellent thai speakers here!) will her Thai be up to scratch - they will also greatly respect the fact that she is seeking the money's return for (as they understand things) *her* needs. Hmmm. He may well be onto something. Anway, I've heard of someone who tried to get his deposit back but didn't remind them in advance that he'll be needing it on vacating, only to be told to come back next week, as they always, as was written in his contract, return any deposits in cash only - and they would need time (...which wasn't written in the contract) to arrange it from their bank. That arrangement, of course, was just absolutely splendid for him - especially as he was that night to catch a plane back to Europe.. "Sorry, no have cash now. You must to come back next week, khrap" was, I'm reliably informed, exactly as he remembered matters.
6) If you do have the misfortune to damage anything during your stay, do not wait until the day your depart to point it out to them. Confess immediately and try your best to cover the cost of mending or replacement as soon as possible. With a little luck on your side, they should allow your offer to pay, and it then shouldn't affect your deposit later. But don't delay or try to cover up any misfortune (even it was because of an object being flung across the room, following an academic discussion about your 'wandering eyes' after a few beers)
In conclusion, sure, it might seem a little inconvenient to take all the above steps. But if your deposit is important to you, then your chances of seeing it again should be much improved if you take the above steps. There might be a scam I've overlooked, but ultimately it's up to you to be vigilant. Otherwise you'll likely be joining one of the many who inadvertently joins the "doesn't see his deposit again" club. Btw, if I've missed anything I apologise, but please do add your tip to my list to help others who are thinking of renting a room/apt in T'land.
Hope this helps!