Haven't we have enough impostors, scammers and bots already?'
I suspect they're going to start fighting for their rights..
An email confirmation won't solve the problem, but should at least slow them down.

What happened?

We need this :https://www.youtube.com/watch?v=WqnXp6Saa8Y

This could work actually ; ) Except I am getting paranoid, nothing unusual really..
Trading/scammers threads are still flooded with one-time accounts created by two losers, competing who's bigger one.

I can attest to this being a problem. I started trading today, only to be scammed by two people in the span of an hour. Later on I found out that these were impostor accounts.

How will an E-mail confirmation prevent this from happening? E-mail accounts are pathetically easy to come by, all you need as a few throwaways and you can still make as many imposter accounts as you want, with or without a confirmation. It might slow down bots, but we hardly have problems with those. It won't do a damn thing to stop the human problems on the forums, which are the real issue here.

I've seen your post, and dozen of dozens other posts..
Very sad to hear that, but people should be more careful, seriously. We have this one particular loser hanging around for about nine months..

I definitely get that. I just wanted to display some good will and not be a jerk to others who wish to trade, but that method isn't quite working out. Any tips for how to avoid this going forward?

First of all, ask for a link to one of his posts on the forum. Hover over avatar and start converstion from there, this way you'll know you're talking to real user, not his impostor. No forum presence and you still want to trade, he'll go first.
There is also My list of people I've successfully traded with worth to check before you decide to trade..
And you can always ask one of the the respected community members to be a middleman..

Eh while I think it might slow down bogus account creation (not by much though), as far as trades go the real issue won't be solved or at least improved unless GOG implements some kind of real trading system. Which they should, as long as they do it in a good way. Game keys are always going to be abused when you don't know if you can trust the other people your trading with.

Thanks Mike! This is very helpful! I will use this going forward :)

Something tells me that OP hasn't heard of 10 minute mail.

Surely nothing won't stop loser from scamming.
It's just unbelievable how many people got scammed lately..
I did, easy to filter and ban.

In that case, still, it's not exactly difficult to make multiple email accounts. I agree with BKGaming, while it might slow things down a bit, people will still get scammed unless GOG implements some form of system, which they're probably not going to do for a couple of years since their primary focus right now is Galaxy.

People will still get scammed no matter what GoG do..
Slowing down creating accounts on the go is still better than nothing I believe, and won't hurt honest users at all.
Actually the opposite, because of Galaxy GoG team is working on some kind of public profiles as far as I know, this could be very helpful when trading. And I completely agree, we need a proper trading system, people will trade no matter what : )
I think steam trading system worked very well, until got unecessary overcomplicated lately..