So, some punters couldn't give a monkeys if the girl enjoys herself or not. No problem, that's the way they like things.
Others have a better time if they think the girl is getting off. This is obviously a significant proportion, or the SAAFE OP wouldn't have posted in the first place.
In this group, there's going to be a range - some will be good at pleasing women, some will think they're good, others will know they aren't :-)
Quite a lot of WGs will still want to please the punters in the last 2 categories - after all, if they succeed in convincing these punters that they've got the girl off, they're going to get repeat business.
That still leaves _some punters who are actually good in bed.
Of course most of us would like to think that's us...