I think it's because most people are followers and not leaders. They are lemmings. Also, most people that say "HHO doesn't work" or "HHO is a scam" haven't got a clue on how it works or why. They just want to stir the pot.
HHO works and the
HHO reviews on this site is dedicated to helping people learn how to convert their car without getting ripped off as there are so many junk products out there and just a few that are any good. That's also a reason people give HHO a bad name. It's because they tried a junky product and didn't try to learn what products are the best ones.
Bob Volk's HHO Kit is by far superior than any other one on the market today.
EddieRock