Mixed-material items, like a plastic bottle with a non-removable rubber top, are not recyclable because:
  1. They cannot be sorted correctly
  2. They cannot be separated mechanically
  3. They melt or behave differently during processing
  4. They contaminate valuable recycling streams
  5. They undermine the economics of recycling
Even if the main body is recyclable, the combined item is not. If the components can be separated, then recycle the appropriate part.
No. When people put non-recyclables in the bin:
  1. Workers must pull them out manually
  2. They slow down sorting lines
  3. They increase contamination rates
  4. They reduce the quality of recycled plastic
When in doubt, throw it out.
While glass is infinitely recyclable, there are several reasons why it is not accepted by local recycling companies.
  1. When glass is tossed into the same bin as paper, plastic, and metal, it shatters during collection and transport. Those shards embed into paper and cardboard, ruining the resale value of all materials in the load. Cities must then pay to clean contaminated glass (expensive) or landfill it (cheap).
  2. Glass has low market value but high weight, so hauling it long distances to a glass processor often costs more than the material is worth. If a city is far from a glass beneficiation plant, recycling becomes financially impractical. 
  3. To make new bottles, glass must be:
    • cleaned
    • sorted by color
    • free of ceramics, metals, and non‑glass contaminants
Single‑stream systems rarely produce glass clean enough for bottle‑to‑bottle recycling. Many facilities end up with mixed, dirty glass that can only be used as low‑value aggregate
Profitably recycling #3-7 requires buyers, sorting technology, and market conditions that not every city's program has access to. In the US, #1 and #2 have well-established, profitable resale markets. Plastics #3-7 are a much tougher sell: they're worth less per pound, the buyer pool is thinner, and #7 in particular is a mix of different resins that can't easily be melted down together.
Clamshells and other non‑bottle #1 & #2 plastics differ in shape, additives, contamination risk, and melting behavior — all of which make them incompatible with many local recycling systems.
No. Fluorescent, neon‑bright, and very dark papers are not recyclable, even though they’re “paper.” The dyes and pigments they contain can contaminate the recycling stream, and many U.S. recycling programs specifically exclude them. Additionally, metallic, glitter, and coated paper are not recyclable.

Brown paper bags are recyclable with cardboard, as long as they are not contaminated.