You're not suppose to grease the pulley's. They have sealed bearings. When they go bad you have to replace the whole unit, or have new bearings put in. It's easier to just change the whole thing. Spraying Liquid wrench or anything on the belts or pullies is not a good idea. You shouldn't "lube" anythng that has to do with the belts or pullies. I always hose my engine bay down with water, with the engine running. Depending on the grease you used, it's probably going to be a pain to clean up.
I'd try and wash down all the pullies real good with dish soap/water and replace the belt. Usually the idler pullies go bad. I've used them from Autozone, but never would again.