I worte some qciuk and dtriy prel to tset the theroy that its the shape of the words that cunot. Pretty raadeble. On the ohter hand, not vrey mnay lettres get seihctwd anroud, so of cuorse its gniog to be pertty raedable. Mbaye if I don’t liimt each ouptut wrod to the origianl chraacters:

I woete ssve qwksk aad dkziy pvsl to tmzt the tlrrzy tiat its tte sdmge of tie wozds tixt cnoxt. Pzvlfy rznhmtfe. On tte ofhzr hrxd, nwt vnvy mrry laffmrs gut smhbskrd aczvvd, so of cewrwe ihs gefng to be pmxfty rsrfetbe. Mnjie if I dun’t ldatt ermh ovkqvt wxnd to tke ocdpixml cderxebxxs.

The latter is a lot harder to read, even though the words are still the same shape.

Aptropso of prtty much nithign, bnut interesting I thought.*

* that’s not meant to a Popesian example, just an uncorrected version of my usual bad typing.