I’m looking into this now…
And I have a couple of notes on my experience😂
I do have my own marketing agency and identify band understanding faked accounts became part of the skill set.
Remember ALL accounts are real… however the activity might be easily faked… and is what deems the profile worth it or not.
Note 1: Its actually very easy to start your own Insta account and just buy followers… very fast. Very easy and very cheap. But very pointless. It just looks good… but soon you realise no one likes your posts. 
Note 2 : you can also actually buy activity, them smart developers have helped create a system where they can like and comment on your posts… this gives your image a nice boost… but again it’s not real activity… and it is only for a limited time… (when you stop paying)
Note 3 : some heavy hitter Instagramers can actually quickly make SUB accounts by simply giving a new page a shout out. Hypothetically, for example… will smith 21mil gives shouts out a random page and boom the new page get 30-50k new followers… imagine this process being done by others… ontop of the bots… this is also common… not as empty… but still only a sub account…
Now… I’m the short bit extensive observation of FameSwap… I feel the page is heavily filled with scammers and pointless accounts.
I have had numerous questionable responses requesting For me to directly message the seller on another platform to discuss further… this means you ultimately leave the current FS platform and basically transact away from the escrow platform which acts in a way to protect…
That is always a red flag for me.
But more importantly, I’m my experience and observation, Many of the accounts being sold on FameSwap have been grown by bots and populated by artificial followers, likers and commenters… it’s really not that hard to deduce when you get my points 1 to 3 above…
E.g. many already know that followers can be purchased… but not many realise that post likers and commenters can too… by checking out the likers and commenters you can see that mostly empty shell accounts or forerigh accounts have been used…
And for comments… you can see that a majority of the comments are just standard emojis and responses instead of actual real comments in response to the post…
Ultimately bots and developers do evolve so it’s good to be aware of what is current.