1) The factual and logical content of the Gish Gallop is pure bullshit and anybody knowledgeable and informed on the subject would recognize it as such almost instantly. That is, the Gish Gallop is designed to appeal to and deceive precisely those sorts of people who are most in need of honest factual education.
2) The points are all ones that the Galloper either knows, or damn well should know, are totally bullshit. With the slimier users of the Gish Gallop, like Gish himself, its a near certainty that the points are chosen not just because the Galloper knows that they're bullshit, but because the Galloper is deliberately trying to shovel as much bullshit into as small a space as possible in order to overwhelm his opponent with sheer volume and bamboozle any audience members with a facade of scholarly acumen and factual knowledge.
"Sure we think that they were good folks, but did you know that Washington not only had more than 100,000 slaves, but he also staged gladiatorial games and made them fight to the death? He also ran a network of opium dens and used his gladiators as couriers to deliver opium all over the 52 states. In fact Washington's opium smuggling got so bad that the British had to step in which caused the Opium War that led to the Revolutionary War and John Locke's famous statement that he had to be given the liberty to smoke opium, or he'd prefer death. That also points out another problem, in that most of the Founding Fathers were part of Washington's opium cult and Ben Franklin's most harmful invention was actually a process to purify the active ingredient in opium and inject it. That's right, Ben Franklin invented heroin! What's more, by the time Andrew Jackson was president the US government was so full of drug addicts that they created a soft drink that was just a way to get cocaine into their systems. Don't believe me? It was called Coca Cola because it was a cola with cocaine in it. Go look it up and you'll find I'm right, coca cola really did contain cocaine!"