This man page provokes warnings or errors from man.
"cannot adjust" or "can't break" are trouble with paragraph filling, usually related to long lines. Adjustment can be helped by left justifying, breaks can be helped with hyphenation, see "Manipulating Filling and Adjusting" and "Manipulating Hyphenation" in the groff manual (see info groff).
"can't find numbered character" usually means latin1 etc in the input, and this warning indicates characters will be missing from the output. You can change to escapes like \[:a] described on the groff_char man page.
Other warnings are often formatting typos, like missing quotes around a string argument to .IP. These are likely to result in lost or malformed output. See the groff_man (or groff_mdoc if using mdoc) man page for information on macros.
This test uses man's --warnings option to enable groff warnings that catch common mistakes, such as putting . or ' characters at the start of a line when they are intended as literal text rather than groff commands. This can be fixed either by reformatting the paragraph so that these characters are not at the start of a line, or by adding a zero-width space (\&) immediately before them.
At worst, warning messages can be disabled with the .warn directive, see "Debugging" in the groff manual.
Lintian also stricter in regards to declaring manpage preprocessors.
To test this for yourself you can use the following command: LC_ALL=en_US.UTF-8 MANROFFSEQ='' MANWIDTH=80 \ man --warnings -E UTF-8 -l -Tutf8 -Z <file> >/dev/null