On all of the properties my wife and I have rented out while we were still on the other side, we just took a gamble.

It's a gamble, but the discount is steep. 

Now, with that said, if they have the ability to purchase the property and resell it- that's a different story, but most are having people take their property off the market, on a gamble that they can find a buyer, and then take a substantial amount of the sellers equity for it.

But it is ok with you to gamble with your money sending a ton of mailers and 3%  will contact you?

They will have the systems and experience that goes the xtra mile to uncover as many unknowns as possible, get as close as possible to reliable numbers, and know what that work and energy and execution is worth, which I know to be $$$$.Otherwise, it’s just a gambling exercise between less experienced guys or frankly ‘advantage takers’ hoping they are something they aren’t, and there’s no cheat code to that. 

If you want to take that gamble, then that is up to you.

I do know some investors that try to buy things at assessed value assuming that 20-30% ratio holds true but without more information I associate that strategy more with gambling not so much investing. 

I learned early on from reading blogs such as investfourmore.com that gambling on appreciation is just that, gambling.

Blindly investing in a new market or industry is a gamble; even if it's worked for others.

(Fortune does tend to favor the rich).Only YOU can gauge your tolerance for negative cash flow while waiting for appreciation.For those of us who are paupers, we HAVE to invest for positive cash flow EVERY time (until such time as we can AFFORD to gamble on future appreciation instead)!