Criteria for admission to AP CS courses in high school
I don't have criteria with evidence that are indicators of success, but I have some I use that can indicate the lack thereof.

At my school, although we are not allowed to specify prerequisites for our courses, the other programming teacher and I "vet" prospective programming students using data from students' literacy and math history (the two of us combined teach VB.NET, C#, SAS, and AP CS A).  The literacy and math scores come from the prior year's end-of-course tests.  This data is made available in an interface provided by, I believe, Pearson Education.  For each student we can see something like the following:



Where the colors/shapes mean the following:



We have found that Red or Yellow in math and/or Red in literacy are accurate predictors of a student who will struggle in programming.  Just looking at the data from last semester, when I taught programming I (VB.NET), the only C's and D's I had in the course were the students who had Red or Yellow math scores or Red literacy scores.

Every semester when we go through our rosters (we are doing it right now for next fall), if we encounter a student who has signed up for a programming course who does not have a strong math or literacy foundation, we first approach their counselor, show them our prior semesters' data, and talk to them about the student's chances of success.  The counselor will then talk to the student, and maybe the parents.  Sometimes the student will choose to take something other than programming.  Sometimes the student will want to take programming anyway, and that is fine.  We just want the student (and parent(s)) to be aware that, if they want to be successful in programming, considering their history, they may have to work extra hard or get extra help.

While this process we go through may smack of "profiling", our goal is to help every student be as successful as they can be.

Note that the converse, a student who has all "Green" data, is not necessarily an indicator that they won't struggle.  There are, obviously, other factors, many not quantifiable until you get to know the student:  motivation, maturity, perserverence, and hard work.