If you are looking for what is good and what is bad, you first need to Google what they are selling if you've never heard of it.
Dahlquist is a great example. There are legitimate reviews out there of their products. You could have Googled that on your own before posting it, but you chose not to.
WHY NOT? You're fingers clearly aren't broken. You can search like a mad man on some sites. Now, try Google!
What's tough is to recognize what a TRUE white van scam product is.
For example:
Brand new, never unboxed, complete Home Theater System (LED Projector + Surround Sound System +72”...
washingtondc.craigslist.org
Then you go to the projector manufacturer's website:
You go "WOW! That's some great stuff and a great price!!!"
You've been duped.
No real reviews in the world. The website, when you start looking around it, you find out that there is no manual. There is not an actual way to get in touch with them. Much of the website is a placeholder from when the site was built. Phone numbers on the website are 100% fake numbers. It's all BS. If you went to any website and asked knowledgeable people, they would tell you that it was a scam. If you did some homework, you would see that these models appear to be the same sub $100 projectors available from China on Amazon.
But, there it is. A complete scam of a product being sold on Craigslist for unsuspecting sucker for $3,500. With a 72" screen!!! Wait, can't I buy a 85" television for less than the $3,500 price they are asking for? Really, this is bad juju.