When you get your replacement scope, you might want to avoid using window cleaner on the screen. It's not a windshield.
Window cleaner is one of the best cleaning things around for this sort of thing.
No, it's really not. Most window cleaner is made for glass and contains ammonia, or other chemicals that can etch plastics and cause them to fog. That's assuming there's even a clear, hard plastic window over your LCD in the first place, which is rarely the case. Using a cleaning solution not specifically designed for a bare LCD can eat away at the protective coating and will damage it with repeated use.
Ideally, you would use canned air to remove any dust and debris, followed by a dry microfiber cloth, to remove smudges.
For stubborn stuff, like greasy fingerprints, you can mix one or two *drops* of unscented dish liquid (Dawn is very good for this) in a spray bottle with *distilled* water (tap water contains minerals, which is what causes water spotting when it drys). You could also do a 1:1 mix of ~20% Isopropyl Alcohol and distilled water (giving you a 10% Iso mix); the alcohol speeds drying and helps with grease!
The above recipe also works well for for clear polycarbonate (such as eyeglasses), just make sure you use a clean microfiber cloth free of any hair or dirt. (Personally, I use ChemWipes to clean my glasses, screens, etc.) Do *not* use paper towels or toilet paper, it's abrasive!