How many days of not showering/washing could you get away with before things get terrible? Assuming you’re otherwise living life normally: changing clothes, applying deodorant etc.
I would feel terrible after a couple days, but I don’t think I’d be outed as a non-washer for a good week, maybe even longer if it was a week without being crammed into overly warm tube trains.
For the purposes of this thread let us assume we’re not talking about extremes in temperature. So mild spring, let’s say.