My grammar sense is tingling

Yesterday was a bad grammar day. I kept on noticing so many little grammar mistakes everywhere I went, and it really annoyed me. By far, however, the largest one was pointed out to me by my coworker--this sign on the front of our GM dealership.

Take a moment to look at it. "Last year GM more than doubled the sales of it's nearest competitor." Firstly, there's the glaringly obvious mistake: "it's" means it is. In context of the sentence, I believe they meant to use "its". This is a common mistake for reasons that escape me--how hard is it to memorize when to use its and when to use it's? :wacko:

Now read the message again, slowly. What do you think it is saying? GM has more than doubled the sales of its competitor? To me, that sounds like GM has more than doubled its competitor's sales, which is to say, its competitor's sales have been doubled because of GM. So now GM is helping its competition? :ermm: Right.

So I decided that the only thing to do was to ask about it. Today my friend Alex and I went to the GM dealership and asked about the sign. They were really quite pleasant. An artist from Saskatchewan hand-painted the sign right onto the glass. They were aware of the grammatical error but not the phrasing issue--the sentence itself comes from a GM report. The general manager wasn't in, but I did get his business card. I didn't want to make a big deal out of it--I was just curious, and the only way to satisfy my curiosity was to ask. So far I am apparently the only person to actually come in and ask about the sign. :D