The problem with HSDXD, is not that it has a pervert in it, I've watched plenty with such, and even more with those merely being accused as such... the problem, is with Issei being the main character, and being not just a pervert but a hard core pervert and outright proud of it, but it is told from his mental viewpoint so we get his thoughts and feelings.
THAT, is my problem. Because it utterly destroys story flow.
If Rias is imparting important plot information, or he is in a fight to the death, or some other critical or dramatic moment... these important dramatic or climatic scenes actually get interrupted by his inner dialog on the glories of assets, or rears, or whatever and that he can't keep in control of himself... If he is about to face a strong opponent, he is more worried about 'which side to touch', instead of the more obvious 'how to train'... And death threats against his family makes him more worried about Rias and peerage boobs shrinking.
Had this been told from nearly any other viewpoint, the series would have been better.