Once upon a time were me and my brother, spending time at my grandma's in Romagna. We discovered she pronounced /ʃ/ almost like /s/, and even made fun of that by having her say «Schubert, Schumann e Chopin scioperavano» (IPA /'ʃu.bert 'ʃu.man e ʃo'pɛn ʃo.pe'ra.va.no/, translates to «Schubert, Schumann and Chopin went on strikes»). Another joke that arose from this pronunciation defect, which was shared with grandpa (and I guess is widespread enough among older people of the area, that is of Russi and neighboring towns) was «Perché ci sono i s(c)emi? Perché non tutti sono intelligenti» (Why are there seeds/idiots? Because not everyone is intelligent – semi /'se.mi/ = seeds, scemi /'ʃe.mi/ = idiots).
Later on, I was trying to explain to my dad what a retroflex consonant is in the context of teaching him Mandarin pronunciation, and he compared it to that pseudo-/ʃ/ we made fun of, and I thought «Yep, that's it».
Recently, I was randomly reading about the readjustment of sibilants in Old Spanish (Spanish article), and I tried producing an apico-alveolar consonant, and I was like «Oh, maybe grandma actually had /s̺/ (apico-alveolar), not /ʂ/, as I previously thought.
How widespread is this mispronunciation of /ʃ/ among old people in Romagna, and is it a retroflex or an apico-alveolar consonant?
But it doesn't end there. Recently, I was re-listening to this Hakka song, and I thought I noticed a number of sibilants in the singer's pronunciation, going from plain lamino-alveolar /s̻/ to alveolo-palatal /ɕ/ to some other sibilant which sounded like – wait for it… here it comes… – apico-alveolar /s̺/. So here comes another two questions. Firstly:
Is it possible that some Hakka dialects actually contrast apico-alveolar and lamino-alveolar, with any one of those or perhaps both palatalizing to alveolo-palatals in front of /i/?
And secondly, I thought of those Chinese people who seem to mispronounced retroflexes as alveolars.
Is it possible that at least in some cases the distinction is there but it is not perceived by others because retroflexes become apico-alveolar and alveolars stay as lamino-alveolars?