Re: Good guitarists getting bad advice...
As a guitarist, this has been an interesting thread to read.
I added kick-back legs to my 1x12 combo in order to point the beaming laser of licks at my own noggin, rather than some poor unsuspecting audience member. Unfortunately, I realize, that also points said icepick at my vocal mic. Add to that the fact that my band mates tell me they want more of me (in a 4pc, I'm the only harmonic instrument), and now my guitar is too loud even for me, between what I'm hearing through my amp and whats in everyone else's monitor.
Makes me think of the time I saw Frank Gambale play with Chick Correa's Electrik Band (holy s#!t batman!), and he had his amp downstage next to his monitor, pointed back at his face (think it was a closed-back cab). I haven't tried this, but it seems like it would give the player the benefit of hearing his actual on-axis tone, while keeping the icepick aimed at the null of the vocal mic. It doesn't address the OP's issue of multiple arrivals due to guitar-in-the-monitors though. Anyone have experience with this technique?