The reality is - it doesn't matter. The fact that they have had as many false positives as they have and the way they treat people in general causes it to have rippling effects even for people who are legally here, or are considering legally immigrating.
The risk and level of publicity is just too high for many people to even consider, especially people already intelligent/capable enough to immigrate anywhere else that doesn't have these issues or stay in their own country.
"especially people already intelligent/capable enough to immigrate anywhere else that doesn't have these issues or stay in their own country" Isn't that the point? Come here legally or don't come at all.
Have they had a lot of false positives? Almost every story I see seems to fall apart on further investigation. To be clear, I'm sure they have some false positives, but do they have a lot of them relative to any other immigration system?