Oh, my plugs are very sooty, nice dry black soot! Actually, there's a bit of nice brown color, but not that much.Doesn't look that bad to me but pic's can be deceving.
Post pi'cs of your plugs.
And describe any troubleshooting you have done
They look like aftermarket mufflers (the bike was restored about 8 years and 1000 miles ago).Original exhaust on the bike, or aftermarket mufflers (silencers)? Modifications there to make it quieter (opposite of what most of us do) would have an impact on jetting, but the mixture screws won't have an effect on anything much above idle