Tone sucking is the commonest complaint about wah pedals. The design of the most common "Crybaby" wah and of the Vox reissues is a throwback to earlier years when true bypass was not considered to be an absolute requirement in pedal design. The input of the wah circuit is connected to the guitar signal all the time, and the loading of the wah input affects the treble of the guitar signal disproportionately, giving a deader sound even when the wah is "bypassed".