Your doubletake was justified.
This is the slogan on one of the Clems*n downtown no-smoking ordinance posters.
I read it and, like you, stopped after the first couple of words thinking, "Whose breathing... wait is there a verb missing? Should it be 'Whose breathing is your secondhand smoke?' or 'Whose breathing is secondhand?' or 'Whose breathing is smoky?' ??"
This is because, like most correct English users, my head really could not understand that it was all due to a misspelling. I finally figured it out when I happened to whisper-read it to myself. Then of course my ear picked up "Who's."
So I just wrote them a very nice email down at the City of Clems*n office. I tactfully explained that I believe people take messages more seriously when they don't have misspellings or grammar errors on them. Indeed I'm not so distracted as simply disdainful when I see things like this on anything from advertisements to blogs to quasi-serious info resources (there was something weird on a weather site not long ago but I neglected to note what it was), let alone from governments, albeit local ones. It doesn't make me pay attention - it makes me laugh... ruefully.
Granted I'm kind of detail oriented (some would say overly so - including me a lot of the time) and I'm also kind of a word/language-nerd, so when I say that I probably am in an upper percentile of people who notice these things it is with all modesty - it's simply a fact. I might even be happier if I didn't notice so much of this stuff. But I do.
I do the same thing in French. Sure it's part of my job, but I mean even when I'm watching French newscasts and they are interviewing less-than-well-educated people, for example, I notice their errors (or at least their less polished usages) quite readily, same goes for when I'm in a crowd in Paris and little kids happen to be present. Of course in French I think it's kind of cool - especially from kids - it's as if you're listening to the very essence of living language. We always talk about how language is changing all the time but the language skills and uses of children are changing almost before our eyes (and, some of you will be interested to know, these changes, whether grammatical or even pronunciation-wise - mimic surprisingly well the sweeping linguistic changes that one sees happening over generations or centuries of language use).
Anyway given that I probably notice more of these things than the average bear, and given the fact that I do it in French as well, and possibly notice more readily (or dwell on at least) the anomalies I notice in that language, imagine my surprised delight a few weeks into last year's stay in Paris when I realized I had yet to see A Single Solitary Typo.
A few days later I did see a misspelling on the sign of a little sandwich shop... run by this nice Korean family. In my mind that is the incarnation of "justifiable." Give me a break - it took 3 weeks to see a language error in print in Paris and then only by finding a privately-printed sign at a hole in the wall sandwich shop run by FLE (French as a second language) immigrants?! Is that the coolest thing you've ever heard or what?
It made me really love French people all the more. It also made me oddly appreciative of the more anal side of their nature. I mean, the same mentality that came up with the idea of the Académie Française is probably to thank for the seeming lack of language errors in contexts which, here in the States, are starting to overflow with them (newspapers, commercials, headlines on news shows, magazines, packaging...) Or if that's too on the nose for you, it's the same mentality possessed by sales clerks in NAFNAF (French clothing store chain) who take one look at the top you found and another at your body and somehow both forcefully and tactfully take the top from your hand, replacing it with one you really didn't think looked intriguing At All but when you try it on seems to be a top made by your own personal Top Fairy; indeed it fits you and makes you look better than nearly any top you've ever bought in your life... or at least since your last trip to France. This is the same mentality I lamented on occasion during grad school when working with Frenchies whom I periodically found to be too concerned with the aesthetics of certain things: waiting for a French friend to finish recopying her Proust seminar notes in 10 different colors so we could go to a movie; rolling my eyes at another who freaked when a page of her already-presented paper fell to the floor, causing one corner to crease; spending 400 years fighting with pre-existing oh-so-perfect and aesthetically pleasing formatting on a final exam we needed to refurbish for a new semester (veritable feng shui -- à la française: the arrangement of each set of cues and each vocab bank resulting in the perfect flow of function and text as one traveled through the exam, and the pièce de résistance: a highly complicated and cantankerous table permitting the glossary for the reading comprehension section to be in a finagled sidebar, textwrapped by the reading comprehension passage itself... I know, I'm one to talk! Maybe some of you see now why I am the way I am!... Wait a minute! I seriously think I've got something there - how cool would it be if I could blame all my anal/control-freaky/perfectionisty stuff on prolonged exposure to various former Frog friends and colleagues?! Hmmm. Well maybe not all...)
All this to say that I guess if French people have to be a bit sensitive about doing things "comme il faut" (as they should be done) in order for me to enjoy all the things I enjoy and appreciate about them and their culture, so be it.
Now the real trick would be to apply the same rationale to myself: time to see (some, not all of) my perfectionism in a more forgiving light; obviously it's necessary for a certain level and type of Susancontentment, although it's a chief source of hefty discontent all too often. Hopefully I will continue learning to apply it less stringently, even to ignore it on occasion (and WITHOUT feeling guilty afterwards or viewing the end product as substandard Susan output). I will try to see the merits of going off book more often. I won't quash it completely, but a kinder, gentler perfectionism is not a bad goal, especially if it helps me regard it as an integral and valuable, if sometimes inconvenient, part of myself.
And if maintaining a certain percentage of my perfectionist side means I'll be able to continue contributing to quality control of language use in the world at large, so much the better. I'm pretty sure I can do all that and still keep typos to a minimum.