Correccions

I spit on the street but I don't like to do it.

I don't like to do it in front of people, especially if people are eating some food.

I don't feel polite, it's like unethical and also I don't like when I'm eating outside alone or with my family and someone spits, because if someone does that I'm sure this one is very 'impolite'.

Sometimes people do that on purpose because they are seeing you eating.

I only do that when I'm at home, when I eat something that I don't like but it's rare..

I only do that when my throat hurts or when I really have to spit, I mean, when I have the need to spit.