How to spot a scam

Spotting scams is a difficult thing to do even when you've been identifying them for years!
I just ran into another one of those "This is a scam, mine is not. Go to this website, my web site!
Let me explain: This is for those of us who research a website we find. We go looking for other peoples reviews of that website. We see one that says it's a scam so we open it to find out why. It will usually say only that what you're researching is a scam and that you should go to another site that is not a scam. Sorry but this is a no sell for me! Even though  it might not be a scam, I would not do business with anyone who advertises like that!
Remember when junk mail came in an unmarked envelopes that had a red stripe across the front? I opened these just so I would know who not to give my business too!