Most of those question marks are from copy & paste from who knows where? Apple does things differently, even in e-mails I see the hand of Steve Jobs & his successors.

Just a thought but the problemo may start at the keyboard. Not being a Mac evangelist I don't know, but I suspect it may be a factor. When cutting and pasting (From a Mac) try over-writing apostrophes and quotation marks after pasting and before submitting. See if that improves things. If not, there is little you can do short of techie things like using hash codes.
eg typing :
' for ' - apostrophe
" for " - either quotation mark

Most other problems would be European accented characters and that is universally a problem on the 'Cat. (at the moment)