Actually, plain soap & hot water do an excellent job of cleaning & sanitizing, but bird poop, being what it is, tends to stick better than some other substances and a jet or two of steam helps encourage it to go elsewhere.....
As Chris said, Sharks are pretty good units, though some of the others on the market are not much more than glorified toys.....
Before purchasing, you need something that is rated at 1000 watts or greater (something less cannot generate enough heat to boil water) and has a water storage capacity of at least 16 ounces or more...less than that will have you running for water refills all afternoon...then you have to wait for for steam generation over 212 degrees F.....
Like Mike said, Wagner makes pretty good products.....
If you've bought something you don't think is doing what it supposed to do, take it back & trade up.....