I never touch the glass of the aquarium as the flagtail continuously scrapes off algae and scum wherever it grows!
I have high output lighting on most of my tanks and wow...algae comes in quick and doesn't go away even with presence of bristlenose plecos, but in the aro tank, the flagtail makes it seem like algae doesn't exist haha.
I've had the flagtail for over two years and i've never seen any build up on anything inside the tank (aside from spots it can't reach... like backside of heaters, and intake pipes). Worth the money IMO!