I have discovered a new way to mitigate the dreaded pug healer abuse disease.
If some one whispers "what is your + healing" without first even saying "hello, would you like to heal ..... " I just say no. That just says to me that:
(a) they are rude, and
(b) they tend to wipe and blame it on the 'incompetence/stupidity' of the healer
If some one whispers a somewhat more palatable "Care to ....., what is your + healing", I just give them a + healing figure that is 400 below what I actually heal at. That way if they:
(a) not even respond - then it is their loss and good riddence; or
(b) say "sorry, not good enough" and then not say anything else - then it is their loss and good riddence; or
(c) if they engage in a dialog to see if maybe we can make it work, I then serously consider expending a valuable chunk of my time working through an instance with them .
On the other hand, if some one whispers a reasonably cogent and polite inquiry about how I am geared, and whether I know the bosses, and whether I wish to join them on a heroic, then I without hesitation stock up on the flasks and food and do my best to make it an enjoyable and profitable run for all.
Otherwise I just ignore the "healer" wanted requests on LFG.