You can reinforce data quality by asking each participant to validate his participation by clicking on a link received by mail. As long as the participation has not been confirmed, it will not appear in the Stats of the campaign.
You can activate this option in the "Settings" of your campaign.
This allows you to clear your statistics from spamming and cheaters with invalid email addresses.
Please note that a profile only needs to be confirmed once on all your campaigns. Which means when a participant has confirmed its participation he will not have to do it on any future campaign of your account.