Why "do" people "randomly" use quotation marks "like this"?

I was driving along the highway and saw a sign similar to this: '"We have native corn"', that is to say, a sign where all the words were in quotes. I see this frequently and I have no clue why people do it -- grammatically, it makes no sense, as it isn't a quote, but a statement. Also people will just "decide" to "put" "quotes" around "random" things (or so it seems to "me"). I am not referring to people who (correctly) put quotes around things they wish to highlight as not necessarily genuine, i.e., Michael Jackson's "nose". I am talking about a case where quotes make no grammatical sense and appear to have no meaning. Why on earth do people do this? Do they just want to "dress it up"? Do they want to get "attention"? Is it some perverse form of "emphasis"? Inquiring "-retentive" minds want to "know" ...