I think it's generally fine to interact with ignorant people. What I find the most difficult to deal with, are those who are ignorant yet insist that they know stuff. These people are also somewhat arrogant and most likely (and unfortunately) in position of power. Hence, instead of realizing that they lacking in knowledge, they usually will pretend that they know things and speak in condescending tone.

At work, it is quite common for me to encounter such people. The best way, in my opinion, to deal with them is not to directly confront them. In a one to one interaction situation, just end the conversation and walk away. Subsequently, bring them to a group discussion and try to convince the group. If you are the one who is technically right and have stronger reasons, most of the group will agree with you.

The key thing here is not to be provoked and get too emotionally attached. Drive your argument with logic and you will have the upper hand.