Ive found that some people are politically against Bitcoin and therefore think its ok to say whatever they can to stop it.
More reason to stop associating Bitcoin with any particular political agenda. "Bitcoin will rip down banks and governments!"

You'll catch more flies with honey than with vinegar.
"Bitcoin won't screw you over like Paypal does."
It will screw you over by losing 70% of it's value in 6 hours because MtGox gets DDoSed 
Personally I don't promote it in conjunction with any political agenda.
For example you'll get someone open a bitcoin topic like "What are bitcoins" or "Should i get some bitcoins".
Then you'll get a few people posting the typical "tulips" and "beanie babies" and "no one even knows where they came from", "You'll get hacked!" comments...all of which are allowed to stand.
I'll then refute these with facts about the opensource nature of bitcoin etc.. and how they mined...etc..how to protect your wallet...etc..result: Topic deleted, and "Warned" for promoting a pyramid scheme.