Learning about frequencies is part of mixing guitars.
There's a lot of crap+resonant frequencies you need to suck out of guitars (and every single instrument/track) before it sounds good and sits well in the mix.
Do a narrow band sweep to identify the frequencies then reduce them.
I always cut sub-bass and 4k as a start ( cuz f*** 4K right ? ) then identify the resonant (howling) frequencies and do gentle cuts till they don't bother me or are inaudible in the mix.