Investigator: "What would convince you that bigfoot is not real?"
Bigfooter: "Nothing."
I think you are understating this somewhat.
BF Enthusiast: "What would convince you that bigfoot is real?"
Biologist: "A tissue sample with good DNA of an unidentified animal would get my interest."
Zoologist: "A reliable observation or video footage followed by evidence that any normal animal would leave behind including footprints, hair, dung, and indications of foraging for food would get my interest."
Skeptic: "Any interest by a genuine scientist would get my interest."
BF Enthusiast: "Then you should be convinced already; we have all of that."
Zoologist: "I don't think you understand. You can't take a track from one location and hair from somewhere else and then claim that they are related. An animal weighing hundreds of pounds would need to eat a lot and they would poop a lot. Where are the foraging sites and where is the dung? If I find where elk or black bear have been foraging I won't have to look 50 miles away to find droppings or tracks. Find these in one location and I'll be there to look at it."
Biologist: "Also, if you found a foraging site then there would be a chance of finding DNA left behind that was brushed from the gums or lips. Dung might also contain DNA. Bring me anything that might contain DNA and I'll analyze it. Thus far, samples have been studied in the US, UK, and Switzerland but none turned up any unknown animal."
Skeptic: "There hasn't been any recognition from a genuine scientist. Melba Ketchum claimed that bigfoot had human mitochondrial DNA. She didn't share samples, didn't have any peer review and didn't publish in an actual professional journal. That isn't real science."
BF Enthusiast: "What about Jeffrey Meldrum? He's a real scientist."
Zoologist: "Meldrum has analyzed casts of supposed bigfoot tracks. These casts have short toes, long toes, straight toes, splayed toes, deep tracks, shallow tracks, wide tracks, narrow tracks, pronounced ball impression or none, sometimes two ball impressions, and sometimes with that famous mid-tarsal break and other times without it. I'm not sure I've ever seen two that were alike. With real animals, this doesn't happen. You can easily identify raccoon, beaver, opossum, bear, and mountain lion tracks. Once in awhile you might see a track with a missing toe or other injury but the tracks are more alike than different. With so-called bigfoot tracks we see the opposite where instead of samples converging over time into a bell curve, the distribution is nearly random. That doesn't happen with real animals."
BF Enthusiast: "You just deny the science because you don't want to rock the boat."
Zoologist: "That isn't true at all. It wouldn't even have to be bigfoot. My colleagues would be excited over any new primate in North America even if it was the size of a Marmoset."
Biologist: "Sure you would have some skepticism over the first couple of results but that is what peer review and repeatability is all about. I wouldn't have any trouble getting others to confirm results if I had something to show them."
Skeptic: "Why would I deny science? People make discoveries all the time like finding out that Pluto is not the only dwarf planet or that there are particles smaller than electrons. Finding out something new is always interesting."
BF Enthusiast: "Well, I don't know. You seem to be throwing out a lot of good evidence."
Biologist: "What evidence? Are there any DNA samples showing an unknown animal?"
BF Enthusiast: "Uh, not yet."
Zoologist: "Has anyone found a foraging site with tracks and dung?"
BF Enthusiast: "I haven't heard of any."
Skeptic: "Are there even any videos where the frame doesn't shake and it shows more than a distant, blurry image of something moving in the vegetation?"
BF Enthusiast: "There's the Patterson Gimlin film."
Skeptic: "That was almost 50 years ago."
BF Enthusiast: "Yeah, but what about all those sightings? They can't all be fake."
Zoologist: "Most of those sightings were of people or black bears. There was even a time when people were releasing grown-up pet primates like chimpanzees and orangutans into the wild. Those sightings could have been pretty startling."
BF Enthusiast: "You can't prove they were all fake."
Zoologist: "That isn't my job. My job would be to prove that one is real."