Falcon,
Yea, some guys have a big problem with discoloration. I find that most men, though, only experience a more darkening/bronzing look. Some guys like this look. Hell, I do. I've never had a problem with my dick being darker, and similar to your experience, either has my lady.
In any event, those are some nice words to hear about your "bull sized cock"

True motivation to any PEers ears.
Cheers, and good luck on the 8X7!