It’s always been difficult to provide a good way of letting people preview a texture set before they buy it. I put samples of the textures on the Xstreet pages, but these only show a few textures, and tend to load slowly (possibly because of the amount of traffic that the Xstreet servers are dealing with). I have vendors in-world which display all the textures, but this being Second Life it can take quite a while for them to rez, so going through an entire set can be tedious.
Well, I now have an alternative, in the form of Texture Galleries on this web site. You should see a list of the Galleries down the left-hand side of this page. Each gallery will display a set of thumbnails. Hover your mouse over any thumbnail, and the full-size image will be displayed. Click the thumbnail to be taken directly to the Xstreet page for that texture set.