A Microsoft Windows innovation© and deviation from standard character sets. Smartquotes inserts nonstandard quote characters that fail to render on non windows platforms (e.g. Unix, Linux). The result is nonstandard Microsoft specific HTML that renders like this:

I picked up the dog?s food bowl. It?s strange how delicious the dog?s food looked. But it?s the dog?s food, not mine, so I left it alone.

There is a PERL script to fix this; it's called demoronizer. From the man page:
A little detective work revealed that, as is usually the case when you encounter something shoddy in the vicinity of a computer, Microsoft incompetence and gratuitous incompatibility were to blame. Western language HTML documents are written in the ISO 8859-1 Latin-1 character set, with a specified set of escapes for special characters. Blithely ignoring this prescription, as usual, Microsoft use their own "extension" to Latin-1, in which a variety of characters which do not appear in Latin-1 are inserted in the range 0x82 through 0x95--this having the merit of being incompatible with both Latin-1 and Unicode, which reserve this region for additional control characters.
Of course, Microsoft would say the fix is for all the holdouts to switch to windows. Resistance is futile.