Rust Converting Paint?

[tobyw]

Anyone have experience with any of these "rust converting" paints? I'm not talking POR-15, but rather the spray bombs from Krylon, Rust-Oleum, etc that you can get at your FLAPS or the like... I've got some surface/flakey rust areas on the underside of a rig, among other areas/vehicles, that I'd like to protect before it goes much further. I'm waaaaaaaaay to lazy to get in there and wire wheel it all away and then properly prep/paint, and according to the late night infomercials you can just spray it on an call it a day. Any real world feedback?