What are the immigration risks for returning to Thailand after a short trip to Singapore on a visa-exempt entry?

It is not normal that the immigration officer decides things by the way he is feeling at the time..if he guarelled with his wife before work then he will screw you and not his wife. Not right to run a country 😕

Opinion is that since it is first time you will be fine. Anecdote is that they are tightening up more recently.

I read a post from another who did exactly the same. 60+30, 3 days in Laos by plane. On re-entry he was pulled aside and asked about onward flight booking and his reason for returning. In his case he had been doing Muay Thai training and wanted to do another month before returning to his home country.

They let him through. He was posting because he wanted opinion on doing another border run after staying a further 60 days.

Be prepared to ask questions. I guess if you have 30 day hotel booking and onward flight tickets that will show proof of your intention.

If I was a Immi Agent I would have doubts about what people say and want to see something concrete. Like your post you say you would like to leave for 2 days to Singapore. I read that as you want to stay in Thailand longer and you are going to Singapore as a border run.

you got a return ticket within the time you get stamped in on a visa-exempt entry,in case you get asked, and if your travel history of the recent 12 months is an empty book, you are safe

If you haven't spent additional time in Thailand other than the trip you're currently on within the last 12 months you should be fine.