I totally disagree... what you're saying is mic position doesn't make a difference.
Mic position makes all the difference... but it won't make a bad tone sound good.
One has to start with a tone that is good for recording. Because it may sound good in the room doesn't imply it will record well. Don't be afraid to use more treble than you think you need.
Proof is in the pudding... check my clips in my SIG. If you can't find anything you like, then totally disregard the rest of this. If you find something, then read on.
I'm referring to tracking heavy guitar
Hi Gain levels do not cause thin distorted tones. Thin distorted tones do.
Use Dynamic mics. 57, i5 and md421 are very good mics for this
Condensers do not work as well. I recommend you avoid them.
Moving the mic one inch will make a significant tonal difference.
Hear what the mic hears. Use a descent pair of isolating phones during mic placement. Put the mic in the best spot you can find. I've found very close pointed just off center is a great starting place. Moving away and closer will make a huge difference in the treble pickup. Actually moving out may cause the treble to go up. Don't be afraid to put the mic very close. Moving side to side, again, makes a huge difference in the mids and treble. Less for the bottom.
post tracking... experiment with taming these frequencies
2.3KHz narrow notch
7.5KHz narrow notch
low pass at somewhere between 5K to 7.5K. the better you get at tracking and setting your amp, the less you need this
other frequencies to play with (tame)
400Hz
800Hz
1.2KHz
Hi Pass around 60 to 80 Hz
if the tracked bottom is boomy, put a MBC 270Hz and below and compress... Atk:10ms Rel:50Ms Ratio:~2:1 to 4:1 to taste
Layer two guitars with one scooped and the other with more mids
Heavyness actually comes from the Bass Gtr
Here's a short clip I just tracked a couple of days ago
Clip
Good luck