Yes, I have first hand experience with CLEP tests (and some other similar test by a different name, which I can't recall right now). I took 4 years of college level math from 8th through 11th grades to "prep for college". When I started college, after having not taken math for a year, they gave me a placement test and informed me I could retake advanced algebra or take calculus. Being 18, I was not going to retake advanced algebra. I ended up dropping out of calculus. I was so bitter about the experience I did not take another college math class until my thirties, when I clepped college algebra and got waivered into a statistics class based on my 17 year old SAT scores. I CLEPed some other stuff as well to wrap up an associate's degree and not risk having to start over from scratch if I ever got back to college. It still rubs me the wrong way that a bright student would be told to take yet more advanced math when they already had more math (as I did) than most graduating seniors.
I don't know how you would predetermine which professors are still working professionals. I mostly lucked into that situation, in part by taking classes in GIS, which was apparently still new enough to have lots of working professionals teaching it and not so many full-time professors teaching it.
Sorry for the misunderstanding. I CLEPed several things to wrap up my associate of arts. I don't recall if I CLEPed anything after that, though I did take some additional first year classes....let me see if I can reconstruct the timeline for you:
Took 2 years of college starting at age 18 at the local hometown college. Had no major the first year. Chose a history major the second year so I wouldn't have to change advisors and could largely continue taking whatever interested me. Dropped out because I got married and began following my husband's military career from place to place.
Spent many years checking out every available educational option at every duty station while having babies and doing the military wife thing. Much to my frustration, they never met my needs (will skip the details to try to keep this short).
Showed up in California, where in-state tuition (that I qualified for) at a community college was about $13/credit hour (and later dropped to $11). Talked to a college counselor. Enrolled in two classes and tested out of three others and was given credit for my 2 years of college from when I was a teen to wrap up an Associate of Arts in Humanities in May 1999.
That fall, much to my astonishment, enrolled in a bachelor's degree (I was astonished because I was trying to lock in those old credits for "some day, when I might return to school", which I had not envisioned to mean "like maybe this fall!"). The program: Bachelor of Science in Environmental Resource Management. Environmental studies degrees are typically rooted in geology departments at colleges and tend to be very science-heavy. Since I had a humanities degree, I was missing some of the lower level sciences I needed. I don't recall if I CLEPed any of those. I do know I took at least one such class at a different California community college. This was amidst a huge health crisis, so some of the details of that time in my life are a bit fuzzy.
Later got my Certificate in GIS, the equivalent of master's level work. But I still have not finished my bachelor's, due in part to a divorce and said health issues. I also now have a certificate my employer paid for, which is industry-specific. Employement-wise, no one cares that I have done the equivalent of master's level work. I don't have my bachelor's degree, so it's a big "So what?" My plans: make it on my own, where actual ability to Bring It matters more than a sheepskin.
I don't know how you would predetermine which professors are still working professionals. I mostly lucked into that situation, in part by taking classes in GIS, which was apparently still new enough to have lots of working professionals teaching it and not so many full-time professors teaching it.