It depends on how you do it, if you return after spending just few days in another country and each time stay maximum number of days on exemption, after 2-3 times they will ask you a bunch of questions and possibly give you like 7 days stamp and recommend you not coming back for a while.
If you just fly in occasionally and stay a month or so, can be done up to 6 times. It will look like you're just traveling Asia, using BKK as your "base".
If you do a couple of border runs for a week or two to neighbor countries by *flying* they'll let you back in no problem. It's not cheaper than a tourist visa (but still cheap!) but more fun and less hassle with papers. Too much nonsense needed for a 60+30 tourist visa (if applying by yourself from your country).