There's a modification that you can do yourself to make a wah-wah "true-bypass". Most wahs are not true-bypass, meaning that your signal is still coloured by the wah's circuitry, even when you have it switched "off". The mod seems pretty simple to do. Check out this link: Fulltone.com's true-bypass mod instructions

I have a Dunlop 535Q Crybaby wah, and it's already true-bypass, so I haven't tried this mod yet. However, I did experience the annoyance of having a Dunlop Original Crybaby colour my guitar sound before I got this wah pedal.