I thought I was a bit odd using an old sheet as a cover. Guess not!! Put me down as a sheet user, too. I even snipped a hole for the antenna to poke through. The weight of the sheet tends to give it a bit of a curve if you don't.
I park mine on a rubber backed mat and cover it with a light cotton blanket like they (used to) give you on an airplane. Dryer sheets in the exhaust, Battery Tender, Stabil in the tank, and a bucket of 'Damp Rid' underneath the bike.
Never had problem with rodents, rust, or dead battery.
I agree, the old sheet (or a new sheet) works best for fast on off, and for keeping off the dust if the bike is going to sit for a while. I have a "regulation" breathable cover, but simply don't use it. It's a hassle to get on and off. The sheet does the same thing (inside the garage, that is).
HD breathable cover for me. Gotta agree with a lot of you that use sheets, way less work than getting the cover all around the wheels and exhaust and bags etc... Right now bike isn't covered, hoping to go for a New Year's ride tomorrow if it stays dry and no snow.
I use a HD cover in the garage because my youngest, 4 1/2 loves to ride motor cycles and he will crawl up on the bike if its not covered. I have told him a 1000 times not to get up there when Im not around but I can just imagine it tipping on him one day when Im not paying attention.
So... I cover it. With one that is a pain in the @$$ to put on and take off but its good insurance to me.
I live in a RV park so mine sits under an easy-up canopy and I have found that my cover gets dust under it anyway, which acts like sand paper if there is a breeze so i don't cover it I use a Ca duster and detail spray a lot.