Phoenix
It's not more common, nor is it just guys. I can take you to a dozen reviews written by young BP gals who want to get things going with their business and move from a daily ad based business to a board referal based business.
The reasons fake ads are written is for personal gain of the writer, but despite speculation as such, it's not because someone is a cheap ass.
What are those other reasons? I don't think that sort of info should be posted. It is more to everyone's DISADVANTAGE to give out tips and instructions in a public forum because there are people who want that info for "the purposes of evil" to put it in a tongue-in-cheek way.
(Similarly, I would never a noob any help on a board. One man's noob is another man's undercover leo.)
By the way--- nice diversionary tactic with the statement "This makes me wonder how many of the reviews under reviewers who seems like "veteran" hobbyists are actually fakes ones and just never got caught or called out for it..."
As a non-veteran guy, that shifts the normally greater doubt toward you to a more balanced doubt toward all guys, which can lead some to become more complacent. 
How's that for a conversation you'd like to have while a cop is standing next to you!?!?
After all, that is what all discussion boards really are.
But if you were a veteran, you'd know that! Just sayin'
Bro-hugs!!
Be safe everyone!
HH
...is just good natured ribbing.
You make the most valid point: Removing doubts and establishing safety is what SCREENING is all about.
HH
As a non-veteran guy, that shifts the normally greater doubt toward you to a more balanced doubt toward all guys, which can lead some to become more complacent.