Not every design is going to be a hit, and that's a completely normal part of running a shop, not a personal creative failure — but running a quick, honest post-mortem on a design that's genuinely underperforming (rather than just quietly writing it off or, worse, taking it personally) usually surfaces something specific and useful, either about that design or about your process more broadly.
The first check is visibility, not appeal — is the listing actually getting found at all? Low views combined with low sales points toward a discovery problem (title, tags, or category, see our pieces on Etsy SEO and search filters) rather than necessarily a design-appeal problem. A design that's genuinely never being seen hasn't really been tested yet, and it's worth ruling this out before concluding the design itself is the issue.
If views are reasonable but conversion is low, that points more specifically toward the listing itself — photos, description, pricing, or the design genuinely not resonating with whoever's actually clicking in. This is where checking your photo quality against the mockup-quality issues covered elsewhere, and your pricing against the realistic margin math covered elsewhere, is worth doing before assuming the underlying design concept itself was simply wrong.
If both views and conversion look reasonable relative to your other listings, but raw sales volume is still low, that might genuinely just mean the underlying concept has less demand than you expected — worth checking against a quick search-volume check (similar to the niche-testing process) to see whether this was a demand problem from the start, which is useful information for future design decisions even if it doesn't change the outcome for this specific piece.
What's worth resisting: either endlessly tweaking a design that's had a genuinely fair test and still isn't working, or writing it off so completely that you don't extract any useful lesson from it before moving on. A reasonable middle ground is giving a new design a real, defined testing window (a few weeks to a couple months, depending on your niche's typical sales cycle), doing one honest round of this kind of diagnostic check if it's underperforming, making one round of reasonable adjustments if something specific stands out, and then being willing to retire it and apply whatever you learned to the next design, rather than treating a single underperforming piece as either a crisis or something to obsess over indefinitely.