No, I'm talking about downloaded files. It happens maybe 2% of the time. You can't be sure the indexers are giving you the correct one.
They usually have a very decent moderation and if they say that an entry has some particular resolution/subs/audio then it has it.
Sure, you have to stay as a seeder for some ratio/period in such trackers and can't hit-and-run, but it gives a warm feeling of contributions anyway.