Sheer and mesh fabric do something a plain fabric cannot: they let the camera see past the garment, into whatever is underneath it. That single fact is the reason a search on a sheer top behaves differently from a search on the same top in a solid colour.
This is not the same problem patterns cause. A pattern confuses a search because the words to describe it are too generic. Sheer and mesh confuse a search because the fabric is not the only thing in the frame, even though it looks like it is.
What does sheer or mesh actually mean?
It is a property of how the fabric is built, not a colour and not a pattern.
Sheer fabric is woven or knitted thin enough that light passes through it, even though the surface itself looks smooth and continuous. Chiffon, organza, voile and thin silk are sheer. Look closely and there are no visible gaps, just a fabric thin enough to let what is behind it show through.
Mesh fabric is built from an open structure with visible gaps between the yarns: a net, a grid, a lattice of holes you can see individually. Fishnet, tulle, some athletic fabrics and most lace fall into this category.
Both let a camera see through the garment. Mesh does it through a visible grid. Sheer does it through a smooth, uniform thinness. A garment can be red, black, white or any other colour and still be sheer or mesh, because the property sits in the weave, not in what dye was used on it.
Why does this confuse a search differently than a solid fabric?
Because a solid garment gives a camera one surface to describe, and a sheer or mesh garment gives it two things stacked in the same space.
Snagfit builds a description from what a photo shows: garment type, colour, material, cut, and a few other fields. With a solid fabric, every one of those fields describes the same physical surface. With a sheer or mesh fabric, the colour and texture Snagfit records can be a mix of the garment and whatever sits behind it, a lining, another layer of clothing, or skin.
A sheer blouse over a plain white camisole is the easier version of this. The two layers have different colours, so there is a visible line between them even through the sheer fabric, and Snagfit can usually separate the blouse from the camisole underneath it.
A sheer blouse over bare skin is the harder version. Skin and a pale sheer fabric can sit close together in colour, and the transition between "fabric" and "skin the fabric shows through to" can be too faint to find. The result is a description that either merges the two into one guess, or gets the garment's own colour wrong because skin tone pulled the average toward it.
Why does the garment's own colour sometimes disappear?
Because colour depends on contrast, and sheer fabric removes some of the contrast that makes a colour easy to read.
A dark mesh or sheer garment over pale skin keeps its own colour clearly. Black absorbs most of the light hitting it, so a black mesh top over pale skin still photographs as mostly black, with the skin visible through the gaps rather than changing the recorded colour much.
A pale or nude sheer garment over similar-toned skin is the opposite case. Nude mesh and pale skin sit close together in colour to begin with, and once the fabric lets the skin show through, the two blend into something closer to a single average colour than two distinct things. Snagfit can end up describing skin tone rather than garment colour, or missing the garment as a distinct piece at all.
This is why the same style of top, in a dark colour versus a pale one, can produce completely different results from the same lighting and the same camera angle. The fabric structure did not change. The contrast against the body did.
Why does Snagfit sometimes merge two garments into one guess?
Because the boundary between a sheer layer and what is under it is faint on purpose, and Snagfit reads edges to work out where one garment ends and another begins.
How outfit search actually works covers the general version of this: the tool looks for colour changes, texture changes and outline changes to separate one piece of clothing from the next. A hard edge, like a jacket zip against a shirt collar, is easy to find. A sheer layer is designed to blend into whatever sits behind it, which is the opposite of a hard edge.
So a sheer cardigan over a solid tank top can read as one blended garment instead of two, especially if the sheer layer and the tank are close in colour. The fabric did exactly what it was designed to do. That same design choice is what makes the boundary hard to locate in a still photo.
Does a lining change any of this?
Yes, and it changes it in the garment's favour.
A sheer garment with its own built-in lining, common in some dresses and tops, behaves closer to an opaque one. The lining is the surface the camera actually sees clearly, and the sheer outer layer sits over it as a texture rather than a window into something else. Snagfit describes the lining's colour with the sheer texture noted, which is a much more stable result than an unlined sheer piece worn over skin or an unpredictable layer underneath.
If you know a garment is lined, that is worth remembering when a search result looks more confident than you expected for a see-through piece. The confidence is real: the lining gave the tool something solid to describe.
What can you actually do about it?
Three adjustments, and all of them work by giving the camera more to separate one layer from the next.
Increase contrast between the garment and what is behind it. Where you have a choice, a photo where the sheer garment sits over a colour clearly different from it (a dark mesh over a pale layer, or vice versa) gives Snagfit a real edge to find. This is not always something you control in someone else's photo, but it is worth knowing why one screenshot of a sheer top works better than another.
Choose or crop toward a contrasting background. A sheer top photographed against a wall or backdrop in a colour distinct from both the fabric and the wearer's skin gives the detection a clean line at the garment's outer edge, separate from the harder problem of what shows through the fabric itself. Cropping for a better match covers the general version of this crop discipline.
Crop to the garment's own construction, not to the skin or layer it reveals. A tight crop on a collar, a sleeve edge, a hem, or a seam keeps the parts of the photo that describe the garment as an object, rather than a wide shot where half the frame is the thing the mesh happens to reveal. The construction detail, cut and trim are all still visible on a sheer garment. They are just easier to find in a smaller, better-chosen frame.
None of this makes a sheer or mesh garment search exactly like a solid one. What it changes is how much of the photo is doing useful work, rather than showing Snagfit two things layered together and asking it to guess which parts belong to which. Where a result still comes back merged or off on colour, what to do when you cannot find the exact item covers searching the visible construction detail by hand, which does not depend on the fabric being opaque.