I think this is the baseline.

I definitely am less accommodating than it seems like a lot of people here - I'd rather not swap window for aisle, or non-bulkhead for bulkhead, etc. If I think the offered seat is objectively worse than my current assignment, I will likely decline the request - and I usually select long enough in advance I like my seat. Sometimes a mutually beneficial exchange happens - I was stuck in the aisle on the UD of a 747 when someone wanted to swap from the window so they could get up more. Win-win for me.

Interestingly though, I haven't really encountered most of the hijinks implied in the thread (and DYKWIA). I have only ever encountered polite requests and "poachers" (if you can call them that) who professed confusion when gently confronted and moved to their assigned seat - and I think it was basically always an honest mistake.