Google their name combined with the word complaints - you will see what other people have said in reviews. Of course, you don't know how many of the good reviews are legit, but you can bet the bad ones are by people ticked off at it.
The BBB lists the company as out of business, but similar named companies like hubmailinginc and similar appear to have come and gone over the years - may be a name-skipping outfit.
Some complaints say you have to send $ for a sales kit, then they ask for a processing fee, then sell you a book of sales tips, etc, etc, etc - a common home based business scam technique.
Others says it is like the famous ads that ran for decades in Popular Mechanics and similar mags - send me $5 and I will tell you how to make $1 million. It took the gov decades to shut that one down, because the guy who started it DID make more than a million - telling people to send him $5, then he sent back a piece of paper saying the way to to it is to put an ad in magazines or papers telling people to send you $5 to learn how to make a million $ ! Was actually truthful, to a point, in his case, but essentially a ponzi scheme because more than a few people doing this would run the market out of suckers after a short while.