I've manually cleaned the head on a slim line one after a mouldy floppy disk rubbed against the head and deposited some material - that was one scary operation, used some small foam type ESD cotton bud things that don't leave any fibers behind along with some IPA. From what I recall it even still works with LS120 disks.
Actual regular cleaning disks will destroy the drive though 😀 I think it states that pretty clearly in the manual too.
Agreed that they're the best way to image marginal disks, that's usually what it's used for as well as being much faster than a regular floppy in Windows 10 and with winimage (reads & writes images). In my case I use it as an external drive since my PC is ITX and has no drive bays - the HP USB 2.0 Multibay combined with an HP/compaq LS-120 caddy and external 5v power source. It shows up as Floppy drive B: and a regular USB floppy will show up as drive A:
Whether the drive works in DOS itself depends on the BIOS - a while back I was playing with some LS120 disks on an Advantech PCA-6145 single board 486 which has a bios from around 1998. That one definitely can boot from an LS-120 disk and then access it as drive A in DOS. I was even able to get doom to run from an LS120 on the fastest of my LS120 drives.