First of all, you seem to be devoid of a sense of irony, or humor.
Secondly, one may take certain liberties with informal conversational English. But contractions are neither ungrammatical nor improper, even in formal language.
Thirdly, I was not referring to that specific sentence. In general, your writing is strangely worded and a bit obtuse, you're in no position to deride someone else's supposed "simian language".
Finally, it should read "...there are three mistakes in your sentence. This is how your sentence should look."
First, I do not share your sense of humor. Learn the real definition of IRONY. Just like you needed to learn the real meaning of "dissension." Irony does not work there because you are basing your reasoning on total speculation not facts. Your entire statement is hypothetical logic, so "irony" does not work there. If your statement was totally factual then irony would work there.
Contractions are a sign of a lazy, unskilled writer. Contractions are totally improper considering you are pointing out grammar errors. That guy's syntax was atrocious, I had to read his post three times to understand what he was saying. I was not trying to demean him at all, not in my first post.
You said, "your writing is strangely worded," you mean "syntax." The reason why my writing appears strange to you is because you have not been trained to understand proper English. Half of the time I write in a genre called "cryptic writing," which I do on purpose to fuck with people like you. Consequently, people like you have to GOOGLE everything I write, lol.. There is a certain individual who know's I write in cryptic on purpose. If that individual wants to come forward and vouch for me that is fine, if not, I really do not care because I know I am right.
If I wanted to be an asshole I could rip through your post, it is loaded with mistakes. Why the need to rescue other people or you feeling a little threatened?? Fair warning, stop trying to correct me because you are not qualified to correct me, the next stupid statement that comes out of your mouth I will put the crosshairs right between your eyes. You will end up with a grammar-complex.
Finally, since you said this is informal conversation, IS would work with that sentence. However, in proper grammar you are right, ARE would be correct because the word "three" pertains to something plural. See, I admit when I am wrong.