According to Thai visa and many of the members on the forum some foreigners staying in North Thailand have to register with the Police. The police require photo and finger prints and copy of the passports.
In Pattaya you need to provide proof of staying when staying more then 90 days in Thailand but in Bangkok they have no such rule
Some police in rural Thailand even asked how the foreigners got their money and how he could build such a nice house.
Full story on Thai visa forum
Pete, FrogBlogger
Sometimes the authorities do make farangs feel unwelcome, but I do understand that the Thais would rather not be invaded by some of the dregs of Western society… and quite right true. Western culture is not all it’s cracked up to be, give me Thailand, with all its faults, any day…