Is there "good" and "reasonable" proof of aliens visiting earth?

Everyone above me makes good points. There is no "proof" so far, but history does lead us to believe that it's very possible that we have been visited before. I tend to believe it's possible myself. But so far, there is no hard proof of it. If I were an alien these days, I would avoid this war hunting planet like a plague. Unless I were a warrior breed, like the fictional "Klingons", of "Star Trek" fame. This place would be a cozy rest area for them!