The Dreaded Apostrophe.....

If it needs one, leave it out, if unsure put one in :-)
There is the Apostrophe Protection Society - there is also the Kill The Apostrophe movement - such passion for such a little thing.
I have to declare I am firmly in favour of the little blighter. 
An example - "Residents' refuse to be placed in bins."  but if you leave out the apostrophe, you end up with  'Residents refuse to be placed in bins.' Quite a different meaning."  :-)