Why am I always misunderstood?

I guess since you think that girls are sweet, you talk to them in a sweet way too that's why they think you like them. moreover, its hard to find guys who are polite and sweet in the way they talk to women. mostly, guys who are always polite, sweet and caring towards girls are those who like them so they are having their best foot forward. Well I guess you can be polite in dealing with women but don't treat them extra special so they won't feel too pampered and will not assume that you like them.

I presume you talk differently to a guy. If that is the case, then the problem lies with you. When you talk to a female in a "not normal" way, read sweeter, then there is every chance that they will think you are interested in them.