I'm new to this community and to this sim, so this might be way off, but ho-hum!
If you're able to open the texture map as an image and edit it, maybe you could try increasing the resolution of it, then editing it the way you want it, (with Photoshop, for example)? If the resolution of the image itself is relatively low, it will always look ugly, no matter what you do with it. Without seeing the offending texture or object, I'm not one hundred percent sure what's going on with it, so I might be wrong. I know that most of the time when a 3D object uses a certain texture map, you can change the resolution of that map without altering the positioning of the map on the mesh, so it should be 'do'able. I hope I've helped in some way, or that you manage to sort those damn ugly buttons out!