1) Fraudulent Payment method (eg, stollen credit card)
2) Someone hasn't patched Wordpress (or another app) in 3 years, box gets hacked, then used for bad things.
So, at least with paying via BTC for compute, you pretty much eliminate #1 -- in all cases the provider gets paid, no chargebacks, etc.
Bitcoins can still be stolen (albeit perhaps not as easily as credit cards). But since there's no chargeback system, the victims don't have much recourse.
I would hazard the amount of fraud will go down considerably (compared to credit card fraud) once we've sorted around the best practices for securing your coin.
The same theory applies to credit cards (single-use card numbers, etc)
To address that, I've added a feature that allows private appliance groups to be formed between trusted entities. The Twitter bot thing doesn't use that feature - it's just a way to show off the other stuff I've built to try to get beta testers helping out. You can see the private appliance group feature if you grab an account on StackMonkey. Keep in mind the pool isn't ready for primetime yet...
I fully expect people to abuse and break this stuff. That's what innovation is about, after all.