A product that doesn't give much background on what it is, or how it works, is not as much it and miss to me, but a total miss.
In order for the bacteria transfer process to work it takes several careful steps to ensure that it makes the transition, remember that the nitrifying bacteria naturally found in aquaria are aerobic, which means they need oxygen to some degree (i.e. cannot have an unlimited shelf life) and they are also temperature sensitive so they require some amount of careful handling.
This is basic knowledge about nitrifiers and as more people are becoming aware of it, the companies that actually have a viable product go to the extra effort to explain their process at least enough to show the consumer why their product 'should' work, i.e. dr tim's one and only and tetra safestart, for example.
That said, the few that are tried and true can still fail based on the several variables that come into play when someone attempts to seed their tank.