I wonder if prossies have a similar "dirt bag index" as doctors, which is the number of tattoos multiplied by the number of missing teeth to give the likely days since the patient last bathed.
It's certainly a moot point how long can elapse till you need to shower - unlike the OP I've often been surprised, eg when visiting a WG after travelling to Manchester from Midlands by rail, didn't shower and was then given a good rimming with no complaints. Maybe if you're a clean-looking person (as I am -living in fact) and you smell OK they won't ask you to shower, whereas some people at work reek even after they've showered that morning, one guy was simply dreadful, either he didn't adequately get round all the crevices of his voluminous ass properly with toilet paper after pooing, or he was sweating out the roast beef dinner he'd had the night before, yuk.