It's more about 'how was it maintained?'
A bike with low miles sitting for years is probably going to take more $$$ to set it right, than a higher-mileage, frequently ridden bike which has been maintained.
That bike last powered-up in Geo W Bush's time with 10K miles is gonna take more work than one bought at the same time, which is sitting at 45K miles, and is ridden every season receiving whatever service it requires for another season.
The two things our bikes are subject to are cruddy carburetors (often from deteriorating gas tank innards) and the condition of brake fluid in the front/rear master cyl's, and the hydraulic clutch. If it's at least halfway up the round window with the bike upright, and it looks like apple juice instead of espresso, the hydraulics should work. A fluid change every year or two removes water from the system, preventing corrosion.