Depends how one defines sightings. Must it be a full view accompanied by a photo that looks like a costume? Or just a glimpse of something big moving in the woods?
If one includes all the claims of sightings, I think the majority aren't lying, at least on the surface. I mean, they saw something they genuinely classify as bigfoot, rather than consciously deciding to say they saw bigfoot while knowing they saw nothing or it was a bear, cow, friend in a costume, etc.
Now that doesn't mean that deep in their subconscious they know they're being fooled into believing in bigfoot evidence, like kids starting to realize Santa isn't real but holding onto the fantasy. But how deep do we want to go, before we define them as disbelievers?
It just makes sense. Who are the hoaxers hoaxing? Aren't there more victims than hoaxers? If so, then most people are telling the truth that that shadow they saw on that expensive bigfoot expedition, which everyone else claimed was bigfoot, actually was their own glimpse of bigfoot.
If one or two expedition leaders are lying to fool the rest, for example, why would the rest be lying? Unless it's all an inside joke like the Flying Spaghetti Monster where no one believes (and I don't get that vibe), then surely there are more believers for every liar who's arranging expeditions or putting up websites or writing books to encouraging belief for his own monetary or emotional gain.