Good question Ragnarok. There is actually a fine line here from what I understand that splits very professional guitar players from amateurs. This is actually something I recently learned while experimenting with my playing with distortion turned up. A lot of excess noise / ringing from already picked strings or others that get nudged.

This article is awesome and could be of great use to you regarding your point of interest:

http://www.theshredzone.com/content/article.asp?pageid=265

Many ways of muting excess noise for the right & left hand have been developed over history. You may want to experiment with many of them and find what works best for you.

Good luck on further advancing your sweeping!


Chris