If you can't spell, I will automatically assume I am smarter than you, whether or not that is true. I can't help it. I will give a little more room for someone who is handwriting something, but if you are using any type of email or word processing program, spell-check will HELP you! :)
This also goes for your and you're... and there, their, and they're. But you are pretty much on your own with that one.
Now, you take a look at the back of this van and tell me if you would hire them to do your refrigeration work? [not even to mention the "N" is backwards...]