Small update - though nothing's new to you guys...

At BanLam immigration checkpoint, Cambodia - Thailand border yesterday.

Visa exempt entry person wasn't asked about any proof of three.

Non-x got 30 days stamp (by mistake, maybe) but was corrected to 90days there immediately without any problem.

Person with a few days overstay had no problem out and in, came back to Thailand in 30 minutes. He paid overstay fine at "overstay" counter there when he got stamp out of Thailand at departure passport control.

One guy got some questions about his visa at arrival because he changed visa type recently (questions about reason of change), but came out from arrival passport control without further problem other than some questions and verbal answers.

According to the sign there, BanLam border opens 6:00-22:00. Overstay Fee & Re-entry Permit counters are there just next to passport control counters.