River etiquitte at crowded spots has been bad on the bow for 10 or more years. Being there first doesn't seem to metter to some people, even when there's tons of fish elsewhere. If they see YOU catching fish in YOUR spot, there gonna crowd you and tangle in your lines and do everything they can to try and bust in on the spot that your catching fish at. Then when YOU get pissed off after 5 hours of this kind of behavoir, and have left your spot several times to catch lots of fish where others where fishing and getting nothing, and have the same jackasses continue to step all over you, then the same people will flame you all over internet bulletin boards and in flyshops for years, telling tales of how "you" are a pompous ass with no respect for others, even though it was you who got walked all over.
So yea, river etiquitte's been gone to hell for a long time. I personally go by the rule of, if you wanna fish where I am come talk to me. If you wanna fish where I am and don't talk to me (like all the jackasses on the day I refer to) then I'm gonna make your fishing through where I am a miserable time for you. Anyone who comes up to me and chats before fishing, is more than welcome to fish where I'm at and will probably get info on how deep, what flies, and where....
Etiqutte on one small stream down here I have fished a couple times is, if someone's paked there, don't go... period.