I have applied fluid film in the frame holes and Wool Wax on the outside (frame) of my GX460 twice in the three years I have owned it...one full application early on and a touch-up last Fall.
It does smell bad and it will absolutely ruin whatever shirt and shorts you have on. There's no way around it. I have the same shirt and sweatpants in reserve for whenever I apply them because they are already trashed. Make sure to completely wipe down/hose off your garage floor if you do it inside your own garage. That stuff will track everywhere because it sprays in a mist that travels. Wear eye protection and take a shower right afterwards...before you drive the vehicle.
With that said, the smell will last in the garage/on the vehicle for a couple of days and then it is essentially gone. I applied it on a dry day and then immediately drove on a dirt road to knock down the stink since the dust acted as a scent barrier and also an added layer of protective coating.
Despite the smell, the product itself is great. My frame has 0 rust.