If one was to take a bus/train to say, Phnom Penh Cambodia and fly back into Bangkok, will one get a 30 day tourist visa? Or will immigration issue a 15 day visa? I believe the law states that you only need to fly in for a 30 day visa.

Any responses will be greatly appreciated for 'Food for Thought'.

30-day chop when you fly into Thailand.

Mac

Dependent on your Nationality, it is generally 30 day arriving by air and 15 day by land border.

Its a visa exemption NOT a visa.

Agree with the above, they don't care how you leave, it's how you enter, and it's a "Visa Exempt" entry, not a visa.

As said it is not a Visa and most nationalities will get 30 days entry by air.