I don't know about RV windows doing that but I had a living room window do that-- when I got around to trying to clean it, the glass was etched so badly there was no saving it.
I waited quite awhile before I did mine, so I don't know how long the etching process takes. But if it's "clouded" rather than just wet-looking, your windows may already be etched...
2000 40' Tiffin Allegro Bus \ 2003 Chaparral 260 SSI
1988 53 x 14 Skipperliner \ 1995 32' Party Cruiser
1984 Goldwing Aspencade \ 1976 Harley Sportster