Less or fewer?

Lots of confusion about these two words.  Most of us learned the basics of grammar in “grammar” school back when we were young and impressionable.  So why do most people misuse these two words?  I can see how a lot of people, ordinary folks, can be confused by them.  But, when I hear a commercial substituting less for fewer it really bugs me.  I won’t buy a product from a company who hires an ad agency who, when writing copy, mis-uses less for fewer.  Or when a news reader on TV uses less when they really mean fewer, it grates on my nerves.  It also bugs me when people use “badly” when they really mean “bad”.  I understand that saying “He/she feels badly” about something, they think it sounds more elegant than saying it properly, i.e. “He/she feels bad.” I guess I’m just a fucking purist. There are fewer and fewer (or less and less) of us around and I feel badly about it.  Poor grammar is commonplace and becoming more and more acceptable.  Just not to me