What do you think that most of those websites sends you the surveys to fill out for a few cents running ? Flash ? How much do you know about flash, unless you are a web developer of course, to say if what you are downloading is secure enough, not to steal your identity ? Or when you click on coupons.com etc. coupon printer apps the get downloaded. Once you download and run them, you are giving the app, free rein of your computer. Once run, they are no longer governed by the security controls of your browser. This is how they get to stop you from printing unlimited number of free coke coupons, by hiding the information, somewhere on your storage, even you don't know how to find and delete. It's all about the Benjamins baby.
Anecdote: Do you sleep with me if I paid you $100,000 ? She answers "ummm, yeah, for 100K, I'd sleep with you"; how about if I paid you $10. She answers angrily "what do you think ? you think I'm a whore ?". Oh yes, we have established you are a prostitute. I am just trying to figure out your price.
This ain't anything different. Pay me few bucks and I will surrender my security to you. Then call the IT support, when my computer is running slow and acting weird. No harm to me.