Consider:

Not only do you have to consider a Guest from Sanity, you must consider guests from Santee and Sant-a for that matter. We're all reduced to playing Guests in the annual gift exchange.

Or someone using a amusing Guest name in a humor post for making a point.

Or lost or blown cookies or honest mistakes

Or guesting in on a strange computer

How would these harmless or inadvertant Guests get screened?

Or the mere music browser, sticking a toe in the water?

A total blanket ban would kill or at least delay a lot of good just to discourage a few cretinous scumbags. It would sound like what we condem the CIA or FBI for doing to our privacy, the FCC to our media etc.

Some of the undesireables (to SOMEBODY's tastes) will always find someway in. It's up to the individual to know when to fight back, how to fight back and when not to do a knee jerk reaction to someone pushing your buttons to watch you jump just because they can. Sometimes you make a stand. Sometimes you just walk away. Sometimes you got to take it straight to Joe.