If you talk softly because you are afraid of sharing your ideas or you are insecure, the snob will find it a good chance to make you feel worse. Speak in a steady voice, showing you are not afraid to share your ideas.
However, if the snob is trying to educate you gently about something which you are not really an expert on, it is ok to listen as long as you are not being condescended. Remember that snobs do not only have strong opinions, but they also do not like to have them challenged.
Stooping to their level will make them more sure about their opinions; they will get annoyed, fight back and make fun of anything you say, and that is something you surely do not want. If a snob likes a particular show and you do not agree with him, instead of saying “This show is for losers”, express your opinion in a kind fashion saying “I like another show you need to check it out”.
If a friend of yours is one of these snobby people because there are other good things about him or her, then talk to them about their behavior to see if they are capable of changing.
You can try saying something like “It really hurts my feelings that you tend to think your way of doing things is always the best way”. This may not be easy to say, but it can help the person to change, provided he has the desire.
If you deal with snobby people who do not mind making fun of you and make you and the people around feel small, make sure not to respond when they are being mean, just disengage and let them see you are happy with who you are and they cannot hurt you.