Schadenfreude is German for happiness at the misfortune of others. It seems some people find it funny when other people are unhappy. If you try and educate other people about things you have to deal with they find it amusing.
These people are not worth the effort of letting you get upset by them. If you show them that their comments don't bother you, it will hopefully make them get bored and move on to someone else.
They need to grow up and realise that the world does not revolve around them and other people have feelings as well. They must have very lonely life's if they get pleasure from other people being upset.
The person who is being victimised by the other person is the better person. They should not respond to the snide remarks and let the other person show themselves for what they are. The bully obviously has nothing better to do in their life than upset others.
Why let these bullies think they are big or clever when most of the time they do not have the full facts of the situation and know the truth.