first syllable of 5 phrases begins with S and is pronounced according to the vowel progression a,e,i,o,u, respectively GOOD ONES: Letters from one who is short?
As this theme is covert, it is unlikely to be noticed by many solvers. At 64-Across we get "Alphabet series mystery writer…" for SUE GRAFTON. Might the clue have been used to signal the theme?
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun