User blog comment:B214/Talk About What You Want! 3/@comment-24605349-20141102084543/@comment-24468758-20141104182623

Just comparing him to Sanji you'll see differences in pervertedness.

Sanji tries to flirt with everything female that looks at least a litte bit pretty and has quite the serious delusions.

Issei tried to peek at girls changing and used quite a lot of his free time and money on his collecions. Up to there he rivals Sanji but he overwhelms him by becoming less perverted and yet having even more and even better experiences with girls who want these situations with him.

IMO you can't call him a pervert anymore (as the last time he tried to do something perverted on his own was in Vol 9) except you start calling all his girls perverts as they are the ones to initiate the situations. It's more like natural skinship with the girls that are in love with him and there isn't anything perverted about that.