The belligerent composter

Every few days, a small plastic baggie filled with kitchen scraps appears perched on the topmost morsel in our back-alley compost pile. The scraps are appreciated, but the baggie, tied neatly shut each time, is a minor and thought-provoking nuisance. A good deed packaged in an insult. Our polite cardboard sign specifying only biodegradable materials-- hint: no plastic-- was overturned and another baggie set in its place. Who is this, anyway? A lazy, germophobic environmentalist? A passive-aggressive neighbor avenging our noisy coffee-grinding habits? A hippie-hater enjoying the jam I'm put in: empty the organic mess into the bin and discard the bag, or toss the whole business, earth be damned, and reveal my true colors under duress? Shall I examine the scraps, then smell the breath of passerby to connect the dinner with the compost? Give the bin an impenetrable metal makeover, with password given to only the most trusted? Accept this as my lot for as many years, days, baggies as I live here? Stumped.