(Faces): `facep' returns t for strings that are face names.

lispref/display.texi

@@ -1628,12 +1628,12 @@ particular parts of the text or the frame.
 @cindex face id
 Each face has its own @dfn{face number}, which distinguishes faces at
 low levels within Emacs.  However, for most purposes, you refer to
-faces in Lisp programs by their names.
+faces in Lisp programs by the symbol that names them.
 
 @defun facep object
-This function returns @code{t} if @var{object} is a face name symbol (or
-if it is a vector of the kind used internally to record face data).  It
-returns @code{nil} otherwise.
+This function returns @code{t} if @var{object} is a face name string
+or symbol (or if it is a vector of the kind used internally to record
+face data).  It returns @code{nil} otherwise.
 @end defun
 
 Each face name is meaningful for all frames, and by default it has the