If I see code running alarms automatically sound. Just because it happens on 'whatever' site doesnt mean its 'their' code.
If one clicks on something and you dont think your computer did anything ('because it just disappears'), you are wrong, something has run.
Its very easy for hackers to drop code on just about any site. Hell when one well known antivirus company started out someone hacked in and attached a virus to the product download. So anyone who downloaded the product got a virus!