Gosh, for someone talking about common courtesy, you should show some by politely writing a reply instead of writing in a rash, irate manner towards someone. She/he blatantly did not mean to harm.
Plus, I see lots of people asking about horse critiques for potential buys. This horse is for sale. I could easily the confusion. Also, she says she interested in perhaps buying.
If anything, you should be encouraging someone trying to learn.
I hope I didn't offend you, but I've learned that YOU NEVER KNOW who that person is behind the screen. For all we know, you could have caused this boy or girl to cry, or he/she is from a horrible situation, etc (not saying you, the person who made this thread, are, but you can see my point).