@Tho***
, people usually get the warning stamp from a consulate they hit "back-2-back" over and over without jumping around from consulate to consulate.
Because the consulate doesn't tell you when you pick up your passport that you also got the warning stamp, many people don't even notice it and go right back to that same consulate and get denied. There was a post on a forum a while back where a poster was adamant that the officers at passport control stamped it into his passport. They don't, it's the consulate that does it when you get the visa.
There are reports now that the thai consulate in Phnom Penh will not even issue you another tourist visa if you have a warning stamp from another consulate in your passport. :O