I thought the OP was talking about standard, lead-acid, marine batteries. I have a very expensive battery monitor on the boat. And, when I had a totally dead house battery (1 of 4, 6-volt golf-cart batteries in a series parallel rig) that battery continued to provide readings that would have been consistent with a fully charged battery. Even with a light load, it still provided good readings. The hydrometer, however, quickly revealed one cell was sub-par and failed when under a heavy load.
Granted, you cannot test gel batteries with a hydrometer, but the vast majority of folks that I know don't use them. I guess some folks like sealed wet-cell batteries, but I'm not among them. Kinda' like the "no maintenance" car batteries that tend to die much faster than the traditional batteries that allow you to add water. As for getting battery acid on your clothing--I think I may have done that about 10 years ago, but it may have been longer than that.
I also have a very high-quality digital multi-meter here in the office, one that I use for measuring minute changes in line outputs of audio systems. It was very expensive when I purchased it a decade ago, and I don't take it near saltwater--too darned expensive. I also have an old-fashioned load tester from back in the 70s when I owned a service station. It still works, but I rarely use it anymore.
I guess I'm a bit old fashioned--I'll stick with the hydrometer. I've never had one that failed, and you cannot beat the price.