It isn't only a question about using an image as texture another fun part is displacement, bump, specularity, occlusion maps, manipulating with or without filter, blending, HDR (fake or not), gamma and so on and so forth. There is one caveat about that though, the photo must be a virgin. If someone else has done anything and the image is not longer in virgin shape is it is worthless to you and you skillset is no longer valid.