Let see if we can clear this up.
First off you won't get any email notices on the site. If you see one it's an ad from Google.
Second you will see Private Message (PM) notifications if you have them enabled. First in the header (envelope icon) and if enabled a notification at the very bottom of the page (single line). Also if you have them enabled, you will get a email notification in your regular email client.
Third, the site has specific locations defined for ads to appear. They are top of the page, bottom of the page, top right hand column on the home page, after the first topic listed in a forum and after the first post in a thread. IF YOU SEE AN "EMAIL NOTIFICATION" IN THOSE LOCATIONS ITS AN ADVERTISEMENT FROM GOOGLE.
On mobile devices it's the same story, if a "email notification" appears in an ad location it is an ad from Google.
Lastly, Google's primary business is advertising, and Google Adsense takes delivering safe, virus free ads to customer very seriously. (Think about it if they didn't, it is Google's primary revenue generator) . Granted some of their advertiser may use fear or trickery to get you to click on a link and then make it difficult for you to exit the page that loaded, that aren't delivering a virus. If you suspect something, don't click on it, get a screen shot and PM me and I will contact Google. To date nothing has proven to be a virus.