Better warnings for keyword arguments in presence of :betfore, :after methods

Can you provide an example?

(in-package :cl-user)

(defgeneric f1 (x &key))
(defmethod f1 ((x symbol) &key k) (list x k))

(defgeneric f2 (x &key))
(defmethod f2 ((x symbol) &key k) (list x k))
(defmethod f2 :before ((x t) &key &allow-other-keys)
  (format t "f2 before method~%"))

(defgeneric f3 (x &key))
(defmethod f3 ((x symbol) &key k) (list x k))
(defmethod f3 :after ((x t) &key &allow-other-keys)
  (format t "f3 after method~%"))

compile nil '(lambda (x) (f1 x :bad 1))) ==>
; in: LAMBDA (X)
; (F1 X :BAD 1)
;
; caught STYLE-WARNING:
; :BAD is not a known argument keyword.
;
; compilation unit finished
; caught 1 STYLE-WARNING condition
#<FUNCTION (LAMBDA (X)) {52CDC6CB}>
T
NIL

(compile nil '(lambda (x) (f2 x :bad 1))) ==>
#<FUNCTION (LAMBDA (X)) {52CDC77B}>
NIL
NIL

(compile nil '(lambda (x) (f3 x :bad 1)))
#<FUNCTION (LAMBDA (X)) {52CDC82B}>
NIL
NIL

But it says

5. The use of &allow-other-keys need not be consistent across lambda lists. If &allow-other-keys is mentioned in the lambda list of any applicable method
    or of the generic function, any keyword arguments may be mentioned in the call to the generic function.

No mention that it applies only to primary methods.