The Toronto News is reporting that billiards players have the highest level of pool players testing positive for banned substances.
Part of the issue appears to be the common theme of having a beer or two when playing pool. This would have to be even more prevalent in the online pool world as players are more likely to have alcohol available and with them while sitting at their PC playing. It is advised if you are playing online pool for cash that you should not play while drinking alcohol at all. Any drinking is likely to effect your co-ordination for more difficult shots.