There is more than enough mud slinging going around inside the Dem party... nothing is helped by adding to it with that sort of non-specific accusation.  Yes, we've all seen some rediculous crap make it to the rec list.  The best way to respond is to politely refute it with facts.  Yes, some people get carried away supporting their candidate, but you risk looking like the counter-example if you give in to your urge to ridicule those people, especially if you paint with too broad a brush when doing it.

Remember, we all need to be on the same team come November.