On amplifiers and effects
I've noticed that amps which tend (via distortion and limited frequency respone) to "blur the edges" of your guitar's sound will let you get away with using just about any pedal, whereas amps that are very transparent or "clinical" sounding will emphasize the noise and unmusical distortions introduced by most effects.
Example: My Boogies will take any effect I've thrown at them (see note), whereas my Vibro-King makes my effects sound like dime-store junk. On the other hand, I'd rather listen to the VK without effects than the Boogies with or without.
(note) Most Boogies have a parallel FX loop which simply can't tolerate any effect that has gain.