Whether in pixels or in real world, there will always be scammers.
From the above posts, use MM if the other party is fishy.
But of course, pick your MM as well. Must be trusted in your eyes.
Use your instinct.
I got scammed in my newbie days. About 3 times I believe.
Just some guides that I think would help.
1: If you spotted a scammer and have solid proofs, report them. Grats, you just help Sythe community ban a scammer.
2: Never look in post counts and say they are trusted by their post counts. That is kind of dumb. It is very easy to spam.
3: Always check their vouches. If legit, what kind of vouch, time posted of the vouch, who vouched them, did they went first, etc etc.
4: If possible, never go first.
5: Only go first that you took time to check if they are really trusted. That saves time looking for MM.
6: Never go first to new users. They are the mostly potential scammers. Most of them are just ban evaders.
7: If all else fail, use a really trusted MM. Check the MM's vouches, behavior, post and what kind of post they posted or just spamming non sense.
This things helped me evade scammers.
After I got scammed when I was a newbie, I started using a MM.
And luckily I crossed path with Dark and had him MM for me for a couple of times. Though not for free, at least he accepts RSGP as payment during in time of free trading was still allowed in RS.
After that, I only went first to trusted people, then people started trusting me.
I earned vouches from scratch and hard work.
And I'm darn proud of my vouches.
I hope that helps.