The u-supine can connect with dignus like:
Nihil dignum dictu actum his consulibus (Livy; nothing worth saying/of mentioning was done ..)
But when I tried to use this pattern to say: "No one is worth to be believed easily" I ran into trouble. I have my doubts whether this can be done at all, but if it does I have my doubt between the two options:
Nemo est dignus creditu temere
Nemini est digno creditu temere
The example from Livy suggest the first option might do: "no one is worth with respect to believing" but shouldn't that actually translate to: "no one is worth to believe" ("to believe" not "to be believed"). As something feels missing - the dative. But if it works, can we say with the supine something like: "No one is worth to believe the truth"?
The second example I actually think is not grammatical.
Addendum: The issue at hand seems to be the absence of the "passive gerunds"/supines. For Virgil says:
Superanda omnis fortuna ferendo est. (every fortune is to be subdued by/with endurance)
But if we want to use the gerund passive like: "children (can) see the behind the wall by being carried" we can't say (or can we?) "liberi ferendo post murum vident".
But here the u-supine from Livy suggests the supine can be used "passively". is the "dignus+ u-supine" restricted to passive usage?
Addendum 2: It is not clear the supine can be modified by an adverb as done here, If that's indeed the case, the adverb can be removed.