Parasitic load or bad battery? both? [LX470]

[dperque]

Hey guys - I recently replaced my battery (was 4 yrs old, not driven much) with a Duracell (27F) from Sam's on my 2005 LX470. Since then, if I've had to charge my battery 3 times because of it being completely dead - no click, no turn, nothing. I took it into my local shop and they tested it - said the alternator and starter are fine and that perhaps it's my battery - like maybe I just got a bad one (it's 4 weeks old)

I work from home, don't drive it very much (can go days without being started), but I hooked up a multimeter just now to the '-' terminal and ground wire and got a resting (key out) reading of .56A. That seems really high, but I also didn't let the truck sit long after starting it so there could be things still shutting down.

Anyway, while it was hooked up to the meter, I started pulling fuses one by one - the last one I tried is a 30A fuse labeled BAT and pulling that one dropped the load. 

At this point, I've removed the battery and will exchange at Sam's, but am I missing something here? I've never heard of a "bad battery", but the guy at my shop tells me it happens.

[Lexus Owners Club]

I have come across 'bad' battery cells before and even those which have short-circuited across due to high capacity boost starters which can warp the plates and lead to this.

Also, poor/cheap quality batteries are also noticeable by their weight (e.g. less lead content) which leads to poor storage capacity.