I dunno, a lot (and I mean a LOT) of avocados grow here, and I've never had so much as a remotely metallic taste about 'em...but hey, could be SOMETHING to do with the soil/surroundings/ground nutrients and all that.
Weird.
Fuck the toothpick method - you need climate control if you're growing them that way outside countries that have a lot of heat or sunshine. What you need is to throw 'em underground and let them make their way - the earth has the warmth required (usually) to get 'em off to start.
Just wash them off, dry them out, and when they start to crack, wait another day for good measure, then bury them 4-6 inches under the soil, with the point (that should be the cracked part) facing skywards.
Throwing in a bit of water conserver to your planned "garden" area and some nutrients already in a loose patch of moist, pre-mixed/turned/split/seperated dirt will help too.
That fish emulsion stuff smells like a motherfucker, but I'd throw a bit in - maybe just spray it around the hole you dig? I fin'd it's a great product.
Pyrethrin is a good insect "fuck off" sign, natural, won't spoil the product.
Also...if you haven't seen a fully grown tree, you'll probably want to have a pretty HUGE pot on standby, or at least 5 square feet of land per tree.
That is, unless you micro-grow and want to put waaay more effort into a smaller output/product.
GET netting. Animals love the seeds (possums stole mine at seed stage once), and will go right after the fruit. Nets. Electrify it if need be.
That said, to be honest they seem to lose about 1/3 of their number that won't make it to mature trees...