Just got back from a 2 week trip into Ga and Fla Panhandle. As usual, front of the Lexi was covered with gug butts.
Saw this tip posted on another RV forum and decided to give it a try, and IT WORKS !!!
Get a can of Dow Bathroom Scrubbing Bubbles, and out of direct sunlight, spray the front cap with the Bubbles. Let sit for 15 to 30 minutes. Than take your brush and auto soapy water and brush/clean as you normally would. The gug butts come off much, much easier. Normally I'd have to go over the cap 2-3 times, but had to do it only once this time.
Bubbles break the gug butts down and comes clean alot easier.
For around $3.50 a can, give it a try.
Haven't seen this on the forum here, but if it's a repost, sorry.