Have any of these offers ever not been scams?

It's either a great investment, or a complete scam.

Just got the unit back right before finalizing the eviction to discover that they had been scamming multiple TV/internet providers for the free 3 month sign on period and then switching to the next as there are about 6 different companies boxes that I have to sort through and return as occasionally they stick the bills for equipment with the landlord in our area.

Don't try to scam your way around things to squeeze some extra pennies out of it at risk of blowing up your everything. 

As a first year flipper in real estate; my 1st flip on a mobile home I was scammed pretty badly about $5K. 

Attorney's Office, Central District of CaliforniaFormer CEO of Orange County-Based Private Equity Fund Charged with Conning Investors Out of $62.5 Million via Bogus Promissory NotesSANTA ANA, California – An Orange County man who was the founder and CEO of a private equity fund has been charged with defrauding hundreds of investors out of approximately $62.5 million via a promissory note scam involving real estate, Broadway shows, and cryptocurrency, the Justice Department announced today.Marco Giovanni Santarelli, 56, of Laguna Niguel, is charged with one count of wire fraud.

Home warrantie, offered by builders are more or less a scam, with designed delays and legal loopholes that lead to frustrated tenants.

In a nutshell, don't waste your money, it's all a scam.

And when it is, they declare it some fashion of a scam, hoax, they blame everything but self. 

As far as scams versus actual possibility when getting into a sales position - find a good mentor where you'll both benefit financially as you're getting started in whatever industry it is that you're doing sales in.