Sometimes you get what you pay for. If something is free then perhaps it wasn't actually worth anything?
Without seeming too cynical I am sure you have thought something along these lines from time to time?
I do get concerned when I see Personal Trainers offering (often free) nutritional plans. Whilst many PT's are no doubt giving great advice (and if they are doing that for free then that is a good thing!), I would hear alarm bells ringing if the nutritional advice was suggesting taking specific potions and powders e.g. protein shakes or meal replacement drinks from a particular company. My first question would be "Do you get any sort of commission for this?"
If the anwer is yes I'd walk away (but that's just me....).
If the answer is no then if I did want to proceed I would make sure I bought the said potions and powders from somewhere else - because if they aren't on commission then this shouldn't bother them? (But then again, that is just me....) ;)