I think it has a lot to do with the current mayor, and he's doing a good job.The pavements in the central part of town look good now, and putting the masses of unsightly electricity cables underground was a major improvement.
Hat Yai is no different to many other tourist resorts in Thailand, except that it attracts mainly Malaysians and Singaporeans instead of Westerners.
Lots of Malaysian men regard southern Thailand as some kind of a sexual playground in the same way that lots of Western men view Pattaya.
If not for the sex trade, places such as Dannok on the Thai/Malaysian border would not be what they are today and Hat Yai wouldn't have the amount of hotels, bars, restaurants, massage shops and night clubs that it has.
For younger Thais and Westerners there are typical Thai-style pubs with house bands banging out raunchier music.
Attached to a few hotels are disco-style night clubs but to be honest I've never had the inclination or been inquisitive enough to take a look.
Thai boys - in fact, boys from anywhere - have never done much for me, therefore this is not an area of Hat Yai's nightlife I have explored very much.