Gzipped binaries, shell scripts, anything that "auto" thinks it ought to modify because of the file extension. Modifying transferred files as a default (and without mentioning that the file is being modified) is messed up. When my installation utility eventually unpacks those files and begins to install them, it runs sha1sum on all of them to check for corruption during file transfer. Guess what? WinSCP corrupted some of them on purpose, and my installation attempt aborts. At its most fundamental level (default), a file transfer utility should transfer the file unmodified. If it plans to change the file, it should *tell* you that it's doing that, so you don't waste a lot of time troubleshooting non-existent networking issues.