This kind of PM indicates trust buying (IMO), people who have the intention to have green trust would PM someone just to gain trust feedbacks. Trust is earned along the way when you have more transactions.
While i wouldn't go to as far as sending a pm to everyone i trade with to get a positive feedback, everyone who trades here want to have those green points.
this does not indicate trust buying or any sketchy behavior, i speak from personal experience, i have traded hundreds of thousands of dollars here( yes no typos )i bought and sold thousands of bitmain coupons last year from a large number of members here, i was just a random newbie and sadly non of them was a DT, but there is 1000 times more reasons why i should have my profile painted in green more than a person who happen to buy a 500$ item from a DT member and ended up with a few positive feedback, but i sure won't demand a feedback for every trade, and this is the way it has to go.
This is one of flaws about this DT thing we have, i am very well known and trusted in many FB crypto groups, and just about every large Telegram group that has to do with mining gears, but i chose not to buy something i don't need from a DT member only to get positive trust, so by looking at my profile you would hardly trust me , and you would be naive if you do to be honest, so if i had to go to the extent of pming everyone i trade with to get a positive feedback, i would probably have to excuse myself, tho i sure as hell won't do that.
So people wanting feedback can be for the purpose of making business easier and not having to deal with who would go first or wait for an escrow agent to respond, while i am very certain that many members want those feedback to scam people, so i think one should think 10 times before giving someone the privilege of being trusted by default, even if they had to be unfair to another 10 users by not leaving them a positive.