I have a Dunlop CryBaby wah pedal, and when I play it on a clean channel, it sounds fine, but when I play it with distortion, it sounds awful, like a nasly sound being fed through a tin can. All Im using is the wah and a ProCo Rat II, and no matter how I tweak my amp, pedal, or the settings on my guitar, it always sounds horrible, and I only use mild distortion I have my setup going amp-wah-rat-guitar.
try swapping the pedal order

dont use the rat, wah and amps distortion too
Get off this damn forum and play your damn guitar.
Yeah, switch where the rat and wah are in the chain. So instead of going amp-wah-rat-guitar, go amp-rat-wah-guitar. Thats the way most people run it, and for good reason.