Over distorted harmony: What is the cause?

When I play harmony on my electric guitar through a high gain/drive setting, with a lot of distortion it always sounds horrible and causes a lot of irritating noises. It doesn't make the same noise when I just play singular notes, but when I add a second note over another note when trying to play harmony on a riff it just sounds really bad.

I know distortion and gain are supposed to have an edge to it, but this just sounds really bad. It just sounds like a chain saw or a garbage truck, just rattling and buzzing and really piercing. Are there any specific settings I can use to reduce the amount of unwanted noise when trying to play harmony?

I have an Epiphone Special SG Model playing through garage band amps. I know it's kind of a crappy guitar, but should it be sounding this bad?

Last edited by bachfantasia at Mar 10, 2015,
Quote by Roc8995
Sounds like you need to intonate.

Ah, yes. Just checked it and it does seem to be a bit off. Especially the b and g. I will make some adjustments and see if that helps.