I see a great deal of thread that explain how to avoid the PvP deserter debuff using log out methods, macros, and real ID but I do not see one using the simplest way yet that Ive found, however if this is a re-post I apologize.
All you have to do: Have /afk ready on your chat window, and let someone kill you. Just as you hit 0 hp hit enter and you will leave the BG Deserter free. This has worked for me 100% of the time on a US Server.