Dirty guitar

[GooberNumber9]

I just remembered that according to an Andy Johns interview, the main guitar tracks on Led Zeppelin's Black Dog were not played through a guitar amp, but instead run straight into the mixer and then two 1176es in series to get distortion. Most analog circuits can be hit hard enough to distort in some way, so if you grab some stuff that gives you a lot of gain and then some other stuff that wasn't designed to be overdriven and start overdriving the latter stuff, you'll surely find a sound no one intended you to find.

[KennyLusk]

A relatively clean amp, then slap Stillwell's Bad Bus Mojo on that track and tweak into distortion. I use this from time to time for believable results.

Mostly though, just a Vox amp with the Gain and Volume at settings that are conducive to just a little breakup and the Mid Boost switched engaged.

[Trick Fall]

I used to have an old cassette deck that had 1/4" inputs and I would plug my guitar straight into it and crank the input gain to get distortion. Actually sounded pretty cool.

[vvv]

That's the Codeine (the band) trick.