However, I have never, and never will complete a transaction solely on Telegram. When I was offering escrow services, all official addresses I provided were posted here, on the forum, either in public or through PM, and always included a signed message. If all of us bitcointalk.org members would insist on transacting this way and this way only, the Telegram scams would be a thing of the past. There would be no way for an impostor to fool anyone.
That is my philosophy as well. Unfortunately most people who want to use escrow are newbies and limited in the PM's they can send but I always tell them straight up that I will only leave payment details and the basic information about the deal in bitcointalk PM's. They can respond to it in telegram but I've never posted a btc addy on there for a deal.
At the end of the day, it's quite easy to verify on telegram too... You just have to check that the user is the correct one. This reminds me of when people were getting scammed on steam all the time because someone took the name and avatar of their "friend". A silly scam but way too many people fall for it.