[Dwedit]

Just watch out for the encrypted file formats. Need a debugger to figure out what it's doing.

[lifthrasiir]

They are relatively easier to detect though. Compressed file formats or virtual machine codes in disguise tend to be more annoying, especially since they can look like somehow structured and waste your time.

[Dwedit]

Meanwhile for ZLIB compressed files, just look for the 'x' after headers.