| There are ways to bypass individual effects, and you could in theory bypass all of them and play through a dry/empty patch... There are two things wrong with this: You're still going through the converters (which I found mildly squashed the sound, compared to the beautifully clean bypass the unit has) and 2) you can't cycle through banks/patches while playing clean.
I found this aggravating enough to get rid of mine. I sat down once and compared the GT-10B bypass to every other pedal I owned at the time (Boss buffered pedals, true bypass Fulltone pedals, etc. etc.) and the GT-10B won hands down. Why they would fail so badly on the implementation, I have no idea.
The one small save they made - IIRC - is that you can switch channels of the patch you currently have called up, while in Bypass. And I can't remember for sure, but I think that you can maybe bypass or engage the individual effects in that patch while in bypass also. | 
