I won't add any technical arguments, as they've been well covered by some people here smarter than me. However, a brief lesson per my experience. Some yr. ago, I purchased a bunch of 2 v. batteries, what kind and etc. don't matter. Like those you speak of, they'd been in a large set and not monitored or cared for over a couple yr. They charged up [prior to purchase], looked clean and good [I mean, they obviously hadn't been sitting outdoors under a tree or physically abused, cases clean and clear, terminals clean, etc., all that] and there were I think over a hundred of them. The friend who knew the seller and turned me on to the deal said, well, even if a few cells are bad, you'll be able to set up a system anyway with the good ones, there are so many.
The price was pretty decent, I was very short of cash, and I bit and hauled them home in a couple pickup loads.
Long story short, I was able to use them for almost a year. However, they were junk, it turned out, no matter what I did to "revive" them, and my storage was minimal to the point all I could really run at night [pv charging during day] was some minimal lighting. I wasted my money, in other words, and was left with having to find a place to get rid of them which turned out to be more hassle than it was worth.
I'd have been money, time, and usage ahead of the game to buy either new or demonstrably almost new batteries in a very small set with what money I had, even if that left me dealing with enlarging the set later on and in that case having to run a bank with cells of differing vintage. Live and learn.
By the way, I later purchased a 6 2v. set of those enormous C & D "phone co." batteries that were all the rage in some areas back in the 80s. Those worked out well for about five yr. I got them for about 1/6 the cost of new ones.