How could you watch the rap?
I mean, did you see through the dub? I've never seen anyone interested in One Piece by seeing "that".
I never really took an interest in manga before One Piece, apart from reading a little bit of Dragonbal, so I didn't really know what to expect from the dub to be honest. It was still surprisingly decent, just because it was One Piece and even when you butcher it that badly it still maintains some of its original shine, so I watched quite a bit of it…then I read the manga chapter where Buggy uses his crew to shield himself and I started to discover the difference so I looked up some more manga..
and so I fell in love XD
Also, I think I heard of a few people first discovering One Piece via the dub, so even though it was without a doubt a terrible piece of crap it did at least get a few people into the series...and probably put twice as many off it for life.