Other than to troll lowbie noob snipers, TH trapping is really pretty dumb.
One, it defeats the purpose of a farming base (attackers will still likely take your TH, and those traps/teslas could be better served protecting your resources from inside your base). It also means you are spending extra gold rearming traps each and every defense, which you typically are trying to save while farming.
Two, it really pisses people off (instead of just giving you your free shield and moving on, making your attacker expend more troops makes it more worthwhile for them to raid your base entirely and take more).
Though it can be pretty funny for an occasional few laughs. Other than that though, pretty useless.
The only "pro" I can see really is if you have enough high lvl firepower protecting your TH it will thin out your enemies troops quite significantly and they will have less to use if they were to full on attack you for your storages.
Either way though you still will lose cups the majority of the time, so protecting an exposed TH really gains you nothing.



