You can always search using quotes, lines of text on google and check if that specific word combination is already indexed by the search engine. For example after this post will get indexed or any other content around the web we can copy and paste a line like "Ok I don't usually get mad, but I am mad today! " and see where it was indexed first. Spotting plagiarism is easy these days. The same can be done with images too, you do not need a specific website for that matter. If you see a result from a certain website with the searched description with bold letters, you found the culprit.