Did you really think letting your razor sit on the edge of the bathtub is the proper way to treat a hygiene item? In order to extend blade longevity, avoid rusting, and avoid bacteria garnering on a bare surface that will fester and transfer onto your shaver and then onto your skin, you should at all times store your razor on a clean wash cloth. After each use, rinse your shaver off real well, preferably pre-dry it using a clean towel and then set it on a clean wash cloth that you should exchange every 3 days or so. This decreases the chances of the blades rusting prematurely because it is in constant contact with moisture otherwise, as well as the wash cloth creating a barrier between a tainted surface and an item that one occassionally knicks themselves with while shaving. An even more proper way to store your razor is setting it on a wash cloth on your bathroom counter as opposed to in the shower.
And if the aforementioned doesn’t necessarily motivate you, just look at how gross your shower/bathtub is, then think about that the next time you knick yourself shaving and what you could potentially be putting in an open cut.