The louder he talked of his honor, the faster we counted our spoons

The Ralph Waldo Emerson quote in your question riffs off the idiom to count one's spoons meaning, as others have noted, to check and make sure that nothing has been stolen by suspicious guests. The phrase can be traced back to James Boswell's Life of Samuel Johnson, 1791:

Edit (5/4/12): Note this passage has been turned up 23 years earlier in another Boswell book. See Hugo's link in the comment below.

The spoons being alluded to are no doubt silverware, and are a candidate for theft. I.e., the more he talked about being virtuous, the more certain they were that he was a crook.

The saying is missing an intermediate phrase, which is understood. (I put it in parentheses)

1) "The more he talked of his honor" 2(the more suspicious he was and sounded like a thief) 3) then follows "the more we counted our spoons" (silverware) to make sure they were still there.

My family adored Emerson. I have always taken the saying as meaning, since most families in the U.S. at the time, counted silver spoons as among their most valuable possessions (we have some, nearly transparent with wear),it means the louder one speaks of such as patriotism, the more doubtful we are about the speaker's sincerity as a patriot in the true sense. Very handy for casting doubt in a jocular fashion on reported remarks.