We can cry and rant and rave about "thieves" re-uploading all we want, however, it also takes the rest to take more notice when downloading or liking. For example, if I see something in the gallery I like, I check if there's an original creator. If there is, I'll go to their page and like/download it from them. Not the re-uploader. I'm also not shy to leave a comment telling others to do the same.
It's not difficult. My biggest peeve with it, is seeing a re-upload getting more downloads and more likes than the person who actually spent the day or whatever hours working on it. Especially when it comes to those who are relatively new, or with less than 5 followers, who probably have absolutely no idea because they're either new, or not as involved as others are. It's really quite sad. I see it every where at the moment for actual sims, but house and room people are also in the same boat, and it seems to get less attention (could just be my sim-circle though that makes it seem this way, seeing as a lot create sims, and are far more vocal about it.)
People need to be a bit more conscious, if this happened then I'm sure the trend of 're-uploading for attention' would in part, go away.
