Hi, sorry if this is the wrong place for this but i need help.

I was practicing a hammer on/pull off exercise from mark tremonti in this months total guitar, and on a clean amp setting it sounded okay, but when i turn up the gain, the hammer on and pull offs such sound a mess. Is there any particular amp settings i can use to make the HO/PO stand out and not sound all noisey?
If it helps i'm using a pod xt.
Practice better technique?

Maybe you're accidentally hitting other strings.
Crate GTD65 Amp
RP80 Modeling Guitar Processor

Jack White:
If you think holdin' hands is all in the fingers
Grab a hold of the soul where the memory lingers.
Maybe you're accidentally hitting other strings.

That's my guess; you won't notice it when you're playing cleanly, but when you turn up the distortion you have to make sure you're not hitting any of the adjacent strings.
Call me Batman.