Seems to me that every used battery powered cart is advertised has having new/nearly new batteries. I'd insist on seeing the receipt for the most recent battery replacement, if so advertised, and I'd also inspect the battery date code stamped onto each of the 6-8 batteries. You can google to see where the date code is located... for example, Trojan is a very popular golf cart battery and this site shows how to read that battery date...
How to read a Trojan battery date code | Golf Car Maven
At least this bit of investigation will help you know more about the used cart (and the seller as well).