Traffic Quality groups are defined by sorting COUNTRIES into traffic quality groups. There are 3 quality groups which are represented in index stats with 3 horizontal bars (green=good countries, white=normal countries, red=bad countries). U can edit traffic quality groups in Settings/Traffic Quality.
We also implemented feature to reward trades with better traffic, and on the other hand, send back less to trades with shitty traffic. U can tweak those ratios also in Settings/Traffic Quality in section Traffic weights. Using this feature your sales will go up because more people from good countries will see your site and you will have less interference of bad traffic. After all, the bad traffic quality surfers only waste bandwidth and don't buy anything.