but is this good 'sex' or is it a good 'partner'? Like, good genes, dominant, able to protect offspring, provide resources, etc.? I assume they're doing mate selection based on that, not how much feel-good the peen provides
I'm sure it varies for other animals just as it does for humans. my unneutered male dog's preferred sexual partner, in fact the only other dog in whom he's ever expressed sexual interest, is my neighbor's neutered male, and the interest is very reciprocated.