In many places I see ads for jobs like "paid to click". So basically some people are getting hired to click on ads with these jobs.

Now problem part is some people are paying for those clicks, which really does not convert at all. There are some measures to prevent huge loss of money, like not counting clicks if there are more then certain number of clicks on the same site from the same computer. But that would not really stop the whole scam.

Considering this scenario what can we do to maximize our ROI as an advertiser?

When I do PPC advertisiment, I usually add a tracking number so I can see where the click is comming and I also save the IP address on my DB.

But you have to account for PPC problems, there is no way to prevent the problems.

To some extent you're always going to get your competitors clicking on your PPC ads. Most of the time this will be because your ad is working and you're placed 'above' them in some search that they're doing. But unless you're in some madly competitive, cut-throat, corrupt market, the chances of sombeody sitting there and clicking your ads to spend all your money is fairly slim. However, on saying that, I know it happens and I've seen it done.

You can simply block the IP Addresses from where you get unnecessary clicks.
Or you can inform to Google about that fraud clicks.

Although Google is already using advanced techniques to find out these types of fraud clicks...


So Don't Worry at all...

trust isn't enough, we should know how to use and do it in a proper way.

Don't "trust" that all your traffic is legit. Just like everything else you need to track things. Check out your traffic every day and if you see some wierd spike and you didn't do anything - say launch a marketing campaign - then where did that spike in traffic come from? If it is all from some PPC site from one IP - you know something fishy is going on. Report those things to the PPC site.