Whether it's Bangkok, Pattaya, or other tourist cities, I would say the condo projects most impacted are the newer, massive projects of 500 to 1000 units or more, with the majority of the units being small 25 to 35 sqm condos--which are ideal as illegal 'hotel' rooms. The newer projects also allow a buyer to easily purchase multiple new units all at one time--rather than buying one by one resales from individual owners. This allows these buyers to, in effect, run an illegal boutique hotel within the condo project, using condo staff, and bypassing any hotel regulations, taxes, etc.
I've told this story before. Spouse and I used to own at a then new condo project in Pattaya with over 1200 units, many small in size. At one AGM, a Chinese owner stood up and announced that he paid over 1 million baht in condo fees each year so why shouldn't he be allowed to rent his rooms daily, even if it was illegal?
Well, he answered his own question--it's illegal--but do the math. Supposing his unit average is 35 sqm and the condo fee is 60 baht a sqm, that equates to about 25,000 baht a year in condo fees, per unit. If he is paying 1MB a year in condo fees, that indicates he owns around 40 condos in the project--definitely a boutique hotel that he was--and maybe still is--illegally running. He was not the only one doing illegal rentals in the project and management, at the time, did absolutely nothing.
We had to sell and move--living there was not enjoyable at all as a year-round resident. We now own a house but if we ever buy another condo to live in we will look for an older, well-kept project, with a much smaller number of larger units. For example, something like Northshore, with less than 200 units, with the smallest condo being around 64 sqm--which would be one of the largest in many of the new projects being built. We would also look for a project aggressive against illegal rentals and one that embraces new technology--such as facial scanning--to help fight the problem.