When you paste text in to post, what you slurped as what looked like a regular quote it not a regular quote when pasted, so it comes out as a different character. that's a really simplified explanation.
If you check your post in preview, and just hand-replace the quotes by re-typing them over what you see, it will post fine.
I haven't read the linked article or used the site's recommended above ... but probably the software here just needs a tweak to intercept the bad characters and replace them. in the meantime ... just do it by hand.
I could be wrong about the details of what's above ... but it's something like that ... if you make sure to check your preview, and deal with it, or run your pasted text through the site above, then your post won't show up for others with the weird characters where the quotes should be. (may be affecting other characters ... but same rule probably applies ... )
It’s not only my posts; it’s everyone’s.