Agreed on both counts. I thought that SOP was to re-use test strips, but to spray them with alcohol between uses. At least, that was my impression of the SOP last time I got my hand swabbed in the PreCheck lane.

Those random checks are infrequent enough that misting with IPA between swabs actually has time to sterilize the swab. Alcohols at 70% concentration will kill most germs in 10-15 seconds. But if they are swabbing everyone as they pass through the TDC, and depending on how thoroughly they douse the test strip, an alcohol protocol may not be sufficient to prevent the spread of germs.

I tend not to get too fussed about germs, and I think that people overuse hand sanitizers. The handles on your luggage are probably just as filthy as your average passenger's palm. So even if the swabs are not sterilized, it's near-zero risk compared to other risks you regularly take. (Like touching the filthy tray tables and seat-back pockets in your airplane seat...)

If they are swabbing personal medical equipment, I would insist on watching them sterilize the swab first if I had a compromised immune system.