Generated meshes fail in a small number of recognisable ways. Recognising which one you have tells you whether to fix it or regenerate.
The back is wrong
Cause: single-image reconstruction infers everything it cannot see. Fix: supply a back view via multi-view, or accept it for symmetrical objects.
Thin structures are fused
Chain links, railings, spokes, wire, fingers — come back as a solid mass. Cause: the reconstruction cannot resolve gaps below a certain scale. Fix: none reliable. Model the thin parts separately, or choose a subject without them.
Lettering is wrong
Text on a surface reads as plausible letterforms that are not the letters you asked for. Cause: the image model writes text-shaped marks rather than text, and reconstruction bakes them in. Fix: generate without the text and add it as a decal or as separate geometry.
The object is fused with another object
Two things in one prompt come back joined where they overlapped. Cause: one prompt produces one mesh. Fix: generate separately. This is a prompting error rather than a model failure.
Hard edges are rounded
Chamfers, panel lines and crisp corners come back soft. Cause: reconstruction smooths, and generated normals are usually fully smoothed. Fix: partly recoverable by re-establishing hard edges in cleanup; badly rounded geometry needs modelling.
Lighting is baked into the texture
The model looks lit from a specific direction whatever the scene lighting. Cause: the reference image's lighting is in the colour data. Fix: de-light the texture, or retexture. Prevent it by using evenly lit reference.
The interior is solid or absent
A mug with no cavity, a box that does not open. Cause: the interior was never visible. Fix: model the interior, or pick a subject without one.
The scale and pivot are arbitrary
Cause: reconstruction has no unit system and centres the pivot on the bounding box. Fix: trivial, and always required. Not a failure so much as an unset value.
The topology is unusable
Dense, irregular, no edge flow. Cause: it is a reconstruction, not a model. Fix: retopology. Expected rather than exceptional.