Yup, the very minimum a cache must have, if it is to stand as a final or a trad, is a container and a log book.
If the cache is a waypoint in a multi or offset then a log is not a requirement.
If the cache is one of a series, with each cache pointing to the next, if they are listed as separate stand alones, they require log books.
I am afraid there have been a few, very rare, times when information has been misleading, more common (but still very rare) is when a cache has been muggled and the owner changes the cache page to require an answer rather than a signature but does no change the cache type, or let us know about the change.
For the record I would repeat that instances such as this are rare, and when they are communicated to us and we speak to the owner they are, almost without exception, corrected rapidly.
....I see t'other fat bloke with beard and specs is getting above himself again