google.co.th is an official domain owned by Google. Of course, they're the best out there. Safe site and trusted sources for me. Be aware of the ad results. I wish there were better ways to contact the customer support/help/feedback team.
This is how Google thinks about your privacy:
"If you have something that you don’t want anyone to know, maybe you shouldn’t be doing it in the first place."
- Eric Schmidt, Google CEO
People in countries like Birma, China, Iran, Thailand etc. should be very careful using any Google service.
WARNING: If Google is so wonderful and trustworthy, why is it that they track virtually my entire activity on the web? I don't recall them asking my permission. If you value your privacy on the internet, stay away from Google.