I especially love the ones that spam heals when no one is fighting.
In regards to the proactive vs reactive healer, that's imo a playing style. Hence we have druid and priest combos that do a little of both or better suited to one. Some people are going to find one or the other easier.
Either way, if they keep the party alive, job well done. It's usually easy to tell whose fault it is for dying, but a good healer may be able to keep low/bad tanks and dps alive when they shouldn't be alive
I could really care less if they spam heals when no1 is fighting...as long as I stay alive...
also, I encourage a healer to look more at damage taken part of scrut than anything else, simply due to the fact that some healers just spam tank with heals and use an aoe every now and then to heal rest of party, but if the DPS are taking more damage from aoes than ur OP tank is on boss, then ur healing the wrong people...
also, I encourage healers to keep and eye on warriors and scouts, and other unique class combos, as they essentially cripple themselves to pump out DPS, and many healers don't realise that...
tbh, when I used to be in burn groups, me(scout) popping BA would take almost double the damage the tank takes...and the healer will still be sitting there spamming the tank with heals, watching me bleed out, as I pop phirius pots so aoe won't catch me...