I keep seeing the word "cleaned" in many threads. Is the give-away a lot of handling marks versus what appears to be an almost mint luster? As in a luster that couldn't possibly be there with that much evidence of handling. I had an understanding that a lot of Morgan dollars were man-handled for many years. I'm no expert, and probably would not know a cleaned coin if it bit me. Danka'
There is really no simple answer to your question, it requires experience more than anything. There are a hundred things to know and look for. Do a search of other threads with the word cleaned and you'll find a lot to read. Also, just stick around and keep up with the threads as they progress. You'll get the idea soon enough.