Dave Bonta's "Dregs" is a two-couplet snapshot of a small, odd moment. The speaker looks into a glass and finds a mite, a tiny creature, floating in what's left of a drink. The first lines suggest a rough day before: "yesterday my head / was lighter than my glass." That could mean a hangover's emptiness, or simply a lightheaded, unmoored state. Either way, the speaker seems a bit drained, and the glass, by contrast, feels heavy or still full of something.
Then comes the surprise. The mite is "perfect as an angry letter," a striking comparison. Like a letter, it's small, dark, and sharp-edged, and it seems to carry a complaint. It's also perfectly formed, the way a furious message can be.
The mood is wry and slightly uneasy. The speaker isn't horrified, just struck by the strange precision of the thing. The poem leaves us at the bottom of the glass, with a faint sense of being scolded by something tiny.