There are some folks that are just plain rude and use the forum to belittle people.
There are some that can come across differently than they mean. Written communication is very difficult. You do not have the body language to interpret the text. I teach online and it is not easy to communicate effectively sometimes. People can be much too thin skinned. If you just state the facts, people can think you are being abrupt, even though there was nothing in your message that was rude. Some people need to accept information as facts without any connected emotion.
For example, if you have someone post "Should I Get a Gas or a Diesel Class A?", I think you should be able to post that there has been a lot of discussion about this and a search of the forums will give a lot of information. Some people think this is rude in some way, but I do not think it is. It is helpful information to the poster.