I don't think bad voice acting is an invalid reason to hate dubs. I mean some dubs, anyway. Go watch the Bleach dub for an hour and tell me it doesn't completely effing suck. Then again, sometimes English voice actors are spot on (which makes for a good dub) like in Fullmetal Alchemist. I would also say that subs are preferable because with subs you don't have to worry about the localization and such. For instance, the dubbed version of Zatch Bell is basically a completely different show than the Japanese version.