My nephew and I sort of discussed this same issue about misspellings on signs. What you have to say may have merit, but if you put up a sign about it and you have misspellings and your thoughts are poorly expressed, people will dismiss you as being not credible. I am not a grammar snob. I realize there is the common jargon and that we speak differently according to our purpose and our audience. On FB and emails, we do not always check our spelling, grammar, and punctuation. I am as guilty as most people. And I certainly do not always use proper grammar when I speak. That is okay in casual communications among friends. But, honestly, if I were putting my product and reputation out there for all to see, I would be very particular, as if my business depended upon it, because it just may. And if I were to advertise my product in a foreign country, I would be sure that the person I hire to write about the product is proficient in both speaking and writing in that language.
The reason I bring this up is that I was so irritated by the grammar on a site selling kitchen cabinets, that I actually began writing them to let them know the impression they were giving of their products and services. Then, upon second thought, I decided I may be a little anal about this so did not send my criticism. I am sure they would have made themselves clear in their response to "F*** off!". But still, I cannot help but wonder about why this problem is becoming so common. Is this part of the dumbing down of America?? Or is it part of more and more dependency upon foreign goods and ownership of companies? I don't know.