Are there some bad apples? 

In my opinion comparing USleadList and Listsource is like comparing apples and oranges.

It's just apples and oranges.  

Like any business Re has bad apples, good apples , etc.IF your entire business model whether it being a wholesaler or whatever relies on being in the middle of a property sale/purchase and holding a contract that says as much (lease option, rofr etc) by theory of some on this site and elsewhere you are entitled legally to sell your contract to another as you are a principal in the transaction based on you having paid a consideration to the seller. 

I often hear that letters have a higher response rate, but it's apples and oranges to compare, because the letter might say:"My wife and I want to $$BUY$$ your house..."

There are bad apples in any aspect of business.  

That's like buying Apple stock and calling yourself a market expert.That really depends on when you purchased Apple stock ... when it was $22/share, folks had the same opinion of it as you hear about sub-30K houses/pigs.

This in some studies has been shown to outperform or at worst break even with buy-and-hold investing and is WAY WAY WAY WAY less involved, gut-wrenchingly exhausting, and fraught with those inevitable bad apple tenants. 

I find this metric easier to estimate "apples to apples" is a sense.  

lolif your comparing it to buying apple back in 19???