MI goaded investors into this with the classic bait and switch.

Like much of real estate, it looks a whole lot better on a spreadsheet than it does in real life.It works at scale or with a lot of experience, but you are kind of building a house of cards needing everything to go right in the beginning. 

With the house of cards-like strategy with Tardus, it won't take much for it to come crumbling down. 

Hold on to the cards forever (closing accounts or opening new cards can impact your score).

You screen them the same way a hotel does: not at all.The only thing you need to verify is their credit card number.

I’ve bought some houses with 0% interest for a year credit card loans.

I seem to remember that I didn't even have a business card until then either.You are VERY late to the game to be making these decisions. 

I replied I had credit cards but no photo id.

With risks bring the higher chance the cards will collapse.

If you want a second opinion check credit karma, ask your credit card or your bank.