Our radar is designed to see weather, not other aircraft, so, especially in the automatic modes, doesn't show much of other aircraft at all. You sometimes see jamming when flying in the more military dominated parts of the world. The various VIP jets aren't stealthy at all though, and will show up as well as any other airliner. They also have their TCAS, so that makes them obvious on the screens. The egos show up clearly though, with ATC being forced to allow such important people priority...even to the extent of long holding periods during some VIP movements.
