Contractions again (I am sorry)

I agree that it's useless to add apostrophe-s to indicate is when the word ends in a sibilant (i.e., would take -es to form a plural).  In these cases the apostrophe-s looks very strange, and nothing is gained where pronunciation is concerned.  But in all other cases (regardless of whether they end in a voiced or unvoiced sound), the apostrophe-s for is is fine.  (Go figure!)

*My watch's slow.
My watch is slow.
Dinner's ready.
Mike's here.

My observation is that learners find these nearly impossible to incorporate in their own conversations.  Any comments on that?

CJ

did contracts to 'd informally after sentence-initial question words, especially those that end in a vowel sound.  you need not follow.

How'd he do that?
Why'd she want it?
Where'd they stay?

I'm not aware of cases where, in a question-word + 'd contraction, the 'd means would, but one never knows!   I always put an extra syllable in there using a schwa if I mean would.  Howuhdee do that?   Compare:  Howdee do that?

CJ

some sounds are omitted, some are swallowed and some are combined, the sentences are a mess to my ears.

This sounds familiar!  It has happened to me when I have tried to learn another language.  Only continued contact with the new language seemed to help.  I suspect it's the same for everyone.

Thanks for your comment.

Maple wrote:

I guess the more difficult part of contraction for us is the listening. When you native speakers' speech speed is normal, some sounds are omitted, some are swallowed and some are combined, the sentences are a mess to my ears.

I used to think the same. I always said: "They don't say that, they don't say what they are supposed to say. They leave out sounds, consonants, it seems they speak without even moving thier tongues correctly. I'll never understand a single word, because they speak in an odd way."

Then I found out the truth. They don't speak in an odd way, they speak correctly and naturally. If I don't understand, then I don't know English. Because if I knew it, you would understand, wouldn't I? So I started to learn real American English. Learning how to pronounce words was a shock. I mean, "betty" with a "d" sound? That's totally nonsense! And where is the "t" in "not"? And so on. Then I started to understand and I thought, "Of course I didn't understand, I actually didn't know English at all".

So the problem is that we (ESL learners) are often taught bad English, especially pronounciation. I think we should be taught correct pronunciation before any other thing, and practice listening and spoken English more than any other form of English.
Here in Italy, teachers usually don't put any emphasis on pronunciation, and not much on listening, since they get disappointing results.
I'd like to hear what happens in other countries, but I think I already know the answer. Few teachers teach good English, and most of them are in northern European countries.