Storage units are typically not lighted inside. Even with hall lights nearby for interior units, you cannot see what all is inside that dark storage unit, especially if it is a rather large one. The only way to have any idea what is in there is to have a flashlight handy, and a good bright one at that. You don’t want to bid unless you see and feel that there is value all the way to the back of the unit.
Once you win a bid, you have a short amount of time to remove all the contents. The facility wants that unit back so they can rent it again. You typically have one day to empty it out, so you need to be prepared with the right type of vehicle and helping hands. If you buy a large or a very stuffed full unit, or you buy multiple units, you may want to pay the rent so that you have some time to go through everything.