Online, Bad Company 2 is hack/mod free...but it definitely has some glitches/bugs. Sound went out for me tonight, the game constantly plays the wrong 'You're team won...", "You're team lost" animinations after the match ends, despite it obviously being a
different result. Nothing serious, but they exist. Oh and getting stuck on nothing happens quite a bit as well..
Stay away from CoD. They are littered with bugs/glitches.