I find Karl Meyers likable but not because of charm?
I genuinely think Karl cares for Susan and we saw in some episodes but he had bad habits and behaviour and keeping entertained and chasing the thrill. So he should have stayed single.
I still hate how he treats woman and the woman he dates and he always chasing the thrill it is never enough and has betrayed so many woman it is terrible.
But as terrible as the things he does, he is very much likable. Also it is refreshing because Karl knows he is not all good and kinda seems own it.