My current care factor upon reading this is smaller than a midget.
Dimensional analysis fail!
Anyway, Jo_Vision, I sympathise with you because your problem is an annoying one. If I'm going to do a trick with a colour change I like to cull a few cards so I have a block of red and a block of black which can then be faroed to create a block of cards in red black order. You can do this with the whole pack if you like, but it's not necessary. Then when working with cards from this block, you are pretty much guaranteed a nice contrast with most changes.
Anyway, I thought I would try and post something slightly constructive since so many people seem unable to. Just remember, you don't have to post in every single thread. If you don't like it, ignore it and leave it for those who might be getting something out of it.