Some Protestants just don’t know, others have been misinformed, others know what we believe but reject our interpretation of it.
For example, where we honor and pray to Mary, even though the protestant knows what we believe, they will still say it is worshipping.
But when I speak to my friends who are Protestants, they will say things like:
The Catholic Church added the extra books to the bible at the council of Trent, or they will say, oh, infant baptism, you guys invented that near the time of the plague, because you didn’t want your kids to die and go to hell.
In these cases, when I explain the subject, they reject it for whatever the source is that they are getting their information.
I am not sure if I want to post on some of those other sites, they can be extremely rude to Catholics there, I know there is some of that here, but not to that extent. I can be blunt sometimes in my posts and I read them later and think why did I write that. Too bad my word processor doesn’t have a politeness check to use when I use my spell check.