I had a similar experience with Fox 5.1..
Just after my wife brought a dog home she'd found at a crawfish boil my boss at work had last year, he dug is way out of the yard. After filling in that area of dirt under our gate (but before I "floored" that area with 16 bricks at 3 paverstones) I was trying to come up with some way to keep the dog out of that area, to prevent another large hole under our gate with a subsequent dog chase.
I came up with the grand idea of using a bit of Fox spray and hitting the lower part of the fence and the dirt in that area, figuring that'd keep the dog away until I could better "fortify" his escape route.
Similar to Russell, the wind shifted direction at the last minute, and I got a (granted, relatively minor) blowback of misted spray. This was from a stream dispenser, so it was probably little more than vapor. As soon as a sensed what was going wrong, I instinctivly put my free hand in front of my face, and then, to my own horror, continued the instinct of using the same hand (which had blocked a bit of the spray) to wipe at my face which had started to burn by this point.
Of course, that didn't help matters any as I stumbled back into the house (I couldn't tell for sure thru my blurry vision, but I think I saw the dog laughing at me as I stumbled inside) and over the next 10 minutes, managed to rinse most of the effect away with running water. LOTS of running water in my kitchen sink....
Anyhow, dog didn't mess with the fence, and I was a half hour late to work that day.
I'm about to buy 2 new small fox dispensers (keychain size) and am determined to use the older ones for practice (and see how well they still spray after roughly a year of regular carry). I'll pick a day with NO wind, and use the LARGE field behind my house. Will bring along a camelback of water and a couple of those wipes they sell that's supposed to help, just in case.