Just my 2 cents.
Don't know if a sticker would mean much.
12 volt batteries contain 6 cells; each cell
optimumly produces 2.1 volts. 6 x 2.1 = 12.6
volts - optimum voltage for a battery that's
been inactive a bit, say overnight. This 12.6
figure is straight out of some tech schools books I have. I've seen batteries read 12.7
& slightly higher after sitting overnight.
If one of these off-the shelf batteries you're interested in read 12.6 volts, I'd say you're at least starting off with a healthy battery. Regards.