In Nouns^x, Consonants^x, American English^x

It's not regional (except insofar as it seems to me to be more AmE than BrE) and not sloppy, in my opinion -- unless you want to say also that British speakers who say "choon" for "tune" are sloppy. It is "glide absorption", and it is the sine qua non of authentic American...

In American English, the sound of "s" depends on which sound comes before it. 1. If the noun ends in an unvoiced consonant sound: /f/, /k/, /p/, /t/, /th/-(thin), pronounce "s" as /s/. 2. When it ends in a voiced consonant sound, /b/, /d/, /g/, /l/, /m/, /n/, /ng/, /r/ or with a vowel...