I used to wrap my tape backwards as well because I didn't know any better. It didn't matter until the thicker cork type tape came out and then I found it would curl up at the edges near the brake levers as I spend most of my time riding on the hoods. Since then I've done it "properly" and used electrical tape to finish off and hold the 'bar tape in place with the decorative stuff being just that. It usually peels off after a few rides but I've found the Fizik stuff on my work bike actually does seem to stick.
Mark.