system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why is it so easy yet used so rarely for Starfleet to use surgery to disguise personnel as Klingons or Cardassians or Bajorans or any other species? Shouldn't this be far more widespread in its use?

Though, I also wonder if there's ever any complications from the surgery or the transition back to your normal body.
gpt
A) It's superficial, a basic medical scan will instantly be able to tell.  
B) It's only looks, the person has to be able to talk the talk (both language wise ad cultural wise) and that's not easy.  
C) Espionage can be considered an act of war, and the Federation is not in the habit of starting wars.  
  
That said, all of these things can be overcome, which shows why the technique is sometime used, but it's not used often.