When i play sweet child o mine intro, with the gain on max, the only way to keep it cleam is to never have more than one note struck or in place at once. You have to pick the note then release it and keep the finger that was fretting it on the string- to mute it.
A good example would be Queen Raphsody solo
-------------------15----18--
----------------18-----------
-------------17--------------
----------17-----------------
-----------------------------
-----------------------------
Or something like that!! Basically if you fretted it like a chord with all notes held and picked as one, it would sound awfull and would break up. So you fret the 4th string 17th fret with yer 1st finger and release it but lie your 1st finger over that string immediately after and then go to the next note 17th fret 3rd string with yer 2nd finger!
I duno how to mute or if your supposed to mute with your right hand in this manner.
You could use a wah pedal as a filter to get sharp susained tones a bit cleaner.
Finally, surely people who play on accoustic guitars or in a clean low gain tones will never have to both with these techniques to get clean sustain tones, so doesnt that mean theyl never appreciate what we are having to do?!!
Later Kriss