Look for transparency drops.
Thin clouds and haze often reduce contrast and star quality before they become obvious visually. A timeline view makes these windows easier to isolate.
A stack is only as honest as the frames that enter it. Seestar sessions can include good frames, weak frames and frames that quietly damage the final result. The job is to identify them before stacking, not after hours of processing.

Bad-frame filtering is a decision workflow: identify damage, confirm pattern, keep useful data and reject frames that reduce the stack.
Thin clouds and haze often reduce contrast and star quality before they become obvious visually. A timeline view makes these windows easier to isolate.
Wind, vibration and short tracking events can ruin a subset of frames. The key is whether the damage is isolated, repeated or persistent.
Soft frames dilute the stack. If the quality score drops for a long period, the best stack may use fewer frames but produce a cleaner result.
Open a Seestar folder or any valid Universal FITS dataset.
Find frames marked as weak, borderline or suspicious.
See if bad frames are clustered around clouds, wind, focus changes or tracking drift.
Use the recommendation as a starting point, then continue in your stacking workflow.
Seestar Companion is built for this exact workflow: session verdicts, diagnostics, recommendations and exports without touching original files.