I had this happen to me when I travelled to New York several years ago. I had checked the official US websites that said if you are from a certain group of countries with less than 6 months left on your passport, you could travel as long as you could show your exit ticket.

So, I get to an immigration desk, the agent takes a look at my passport and starts snarling at me that there's less than 6 month left on there. I started to say that on the US government website it said 6 months or less was ok, but he cut me short by say he didn't know anything about any website. My partner was waiting at the end of the desk but he angrily told him to get away from there and get out of the immigration area.

He starts punching the keyboard while scanning my passport. I could see him tense up when he must have read that what I was trying to tell him was correct. He roughly stamped my passport, tossed it to me without looking at me in the eye and yelled next. Charming welcome to the US.

Thankfully not all entries are that bad. Once in Miami the agent saw our passports and said "OMG, are the UK flights landing already? How long have I been here!". And in LA they were very friendly, asking politely about our trip and giving advice on where to go!