It is a best practice for your textures and texture placement to match the preview images with reasonable accuracy. This means that your textures and UVs should be unaltered and applied correctly to the model. Additionally, your UV seams should not be visible.
When customers purchase your models, they have reasonable expectations that they will open and render as shown in the product preview images. If your model includes any of the issues mentioned above, a customer will more than likely request a refund since the model does not accurately reflect what is displayed on the product page.
The majority of our customers come to TurboSquid to save time. Many are working under strict deadlines and render issues take away valuable job time. Customers expect the ability to import the model into their scene without any problems.
Ideal Texture Placement
The image on the left is our context image from the product page. On the right is the output the customer received when they render the model in 3ds Max with V-Ray. As you can see, the render matches the context image, which is the outcome customers expect.
While the texture in the image on the right is applied correctly, the texture has been altered. As you can see, the render no longer matches the context image. This is an issue customers should not encounter.
Obvious Texture Seams
In the image on the right, the UVs have been flipped vertically. This results in a visible UV seam. Again, this is an issue customers should not encounter.
Rotating your UVs will also create a seam. The image on the left shows the UVs in the correct position while the image on the right shows the UVs flipped.