Expressions of bemusement, skepticism, and disbelief:

• Hmm — interesting, worth considering, plausible
• Hmmm — puzzling, intriguing, promising
• Hmmmm — doesn't sound right, long shot, maybe important
• Hmmmmm — unlikely, probably wrong, slim chance
• Hmmmmmm — highly suspicious, major odds against
• Hmmmmmmm — extremely silly, whoa, bogosity-meter-pegging

... worth quantifying? — perhaps begin ~1:1 for "Hmm", falling by a factor of 2 or 4 for each additional "m"?

(cf Classy People (2000-04-01), ...) - ^z - 2018-06-17