Gutter failure is often gradual, which is exactly why it does so much quiet damage before anyone notices. A few signs are worth watching for.
Look for gutters pulling away from the fascia board, visible sagging between hangers, or water marks and streaking on the siding just below the gutter line — all signs water is overflowing instead of moving through the system properly. Standing water in the gutter itself after a dry day usually means poor pitch or a clog somewhere in the run. Rust spots or small holes, more common in older galvanized steel gutters, let water escape exactly where it shouldn’t.
Inside the house, keep an eye out for water stains near where the roofline meets exterior walls, which can indicate long-term overflow damage to the fascia or roof edge rather than a roof leak itself — the two get confused often, since they show up in similar places. If you’re seeing any of these signs, it’s worth having gutters evaluated alongside your roof, since a failing gutter system can undo the protection a good roof is otherwise providing.