Jonathan **************************
@Luc ***********
Thats true *if* you surrender at immigration at an airport (and the overstay is under 90 days).
However, if you are arrested or questioned by officials, and it is discovered that you are on an overstay of *any* length, then you can and will face a 5 year blacklist.
Usually this applied only to people arrested for, say, some stupid drunk shit.
However, there have been people subjected to spot checks (on Samui, for example), and then getting a ban for just a 1 day overstay.