Buddhism and political correctness
This sounds like an issue best analyzed according to the Buddha's teachings on right speech. The Buddha famously expounded how he personally determined how to decide on what to say in the Abhaya Sutta, saying:


  [1] In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial (or: not connected with the goal), unendearing &amp;
  disagreeable to others, he does not say them.
  
  [2] In the case of words that the Tathagata knows to be factual, true,
  unbeneficial, unendearing &amp; disagreeable to others, he does not say
  them.
  
  [3] In the case of words that the Tathagata knows to be factual, true,
  beneficial, but unendearing &amp; disagreeable to others, he has a sense
  of the proper time for saying them.
  
  [4] In the case of words that the Tathagata knows to be unfactual,
  untrue, unbeneficial, but endearing &amp; agreeable to others, he does not
  say them.
  
  [5] In the case of words that the Tathagata knows to be factual, true,
  unbeneficial, but endearing &amp; agreeable to others, he does not say
  them.
  
  [6] In the case of words that the Tathagata knows to be factual, true,
  beneficial, and endearing &amp; agreeable to others, he has a sense of the
  proper time for saying them. Why is that? Because the Tathagata has
  sympathy for living beings."


Source: http://www.accesstoinsight.org/tipitaka/mn/mn.058.than.html

In essence, one should consider four factors of truth, benefit, agreeability, and timeliness. The relevant point here is that even if one might say something that is true, if there is no real benefit to be gained from it, then you shouldn't say it. Certainly not all cases of political correctness fall into this, but it isn't dishonest to hold back from saying something if it will lead to no good.