Good post Ard. Well dressed and maintained lines for that matter certainly can make fishing much easier no matter a single or two hand rod. I know that when I'm fishing spring creeks my line gets cleaned and then dressed every other day or so as the organic matter really can coat the line and impact casting, thus presentation. Of course I dress the line as needed too. Mucillin goes with me on the stream, it keeps the line floating like a cork.
When I wipe down between uses, it's simply warm water and a paper towel, if really dirty I'll use a little dish soap. Now here's where things get a little complicated.
For my single hand lines, I have found that with my Airflo lines, they respond very well to Wiz Lube, which is Airflo's lube, go figure. Noticeably better in fact than the Rio Agent X which I use for PVC lines from Rio and SA. I'd imagine it to work equally as well on the Airflo two handed lines as well. I recently purchased some "El Slicko" from Poppy, which I understand is STP's Son of a Gun. It was noted that it too is very good for Airflo lines so I suspect it, like the Wiz Lube, responds better to the PU that Airflo uses. OCD about my gear? Absolutely!
Back to your point though, no matter what you fish and where, well dressed and maintained line can make a significant difference when you're on the river. My lines are cleaned, lubed and ready to rock. They will be wet from the 4th-12th and well I can't wait!