@Letti0 I have my doubts as to whether guests necessarily notice the specific listing designation at the bottom of the reviews when a host has more than one listing or relists after renovating. They could easily miss that distinction.
@Mark287 As Letti said, do try to upgrade the important stuff before listing. Just because you list it as a shabby, basic place doesn't mean guests won't review it very poorly or arrive, take a look around, and demand a refund. You mention new mattresses as part of the future upgrade. If the mattresses are old, stained, and/or not that comfortable, you really need to replace them before listing. Good beds are one of the most important thing to focus on.
I've seen many businesses fail after just 6 months because they figured they'd open, make some money and then upgrade later. A restaurant with cheap uncomfortable chairs, for instance. Or a junky old floor that never looks clean even if it's just been freshly scrubbed. There's nothing wrong with old, worn and full of character, but uncomfortable, or dirty-looking won't make for a successful enterprise.