That's certainly a consideration. When I hear a Thai voice over the pilot's intercom, I can't help but think about things like how lax the education system is, and how easy it might be to get a pilot's license with good connections (in lieu of actual skill).
However, to put Thai air safety in a broader perspective, check out this link:
http://www.airdisaster.com/cgi-bin/database.cgi
I don't recommend checking it just before a flight, though.