Interesting. Didn't know that. I was thinking fake documents, but after a quick Google search many of these sites say you make a donation to the gov in the country in which you want it... Seems interesting, and probably shady stuff.
I know there's lawyers that specialize in immigration but it's usually a bunch of paperwork and waiting. So I know those types of services are mainly legit.
Yeah, there are some legit ones out there but they're super expensive and unnecessary. The best way is to just do it yourself. Paraguay's pretty easy and comes with some nice perks (fantastic gun laws and no tax on foreign income, for instance).