I have to agree - we *HAVE* to police our own. Also be discrete and use some common sense, and it'll greatly help our cause. If you see a railfan doing something blatantly wrong and quite stupid, tap him on the shoulder and say something - if they give you an attitude, just head to another spot. The local authorities do NOT care who is the good and who is the bad railfan - if they're giving them trouble, they're all getting kicked out, period. They don't have the time or resources to weed out various railfans, so it's much easier to just chase all railfans out of a problematic location.
Rogue railfans in general become famous pretty quick (such as a certain person driving a red Dodge Ram in the Rochester area). No matter what you say to these individuals, they won't change their act. They're usually the ones who get in your face (or the face of authorities) even when they're in the wrong, and are good at dragging down those in the area. Thus, if you see a known "rogue railfan" show up where you're sitting, move to the next crossing - it's not worth the risk. The stupidity and potential harm these individuals create for themselves and those around him (including the railroaders themselves) is ridiculous and often not worth the effort (I.E. standing in the gauge of a main track to get what they consider to be a shot worthy of the cover of Trains magazine). Just be smart, be safe, and be vigilant.
As for calling in defects with passing trains, I know it's a touchy subject on here (especially with employees), so I'm going to avoid the topic entirely...