How can you determine if a ROM is compressed or uncompressed?

[SanguinettiMods]

Yaz0, Yay0, MIO0, zlib, edl, erz, odt, and rnc1/81 are the only compression types I know of or have heard of, yet I can't find any of them in games like Super Smash Bros 64, or Hexen 64, etc. I wanted to know if there was a more efficient way to tell if a ROM has been compressed with a format up above or one that I have not hear of before, or if it just isn't compressed at all.

[xdaniel]

If you can't find known tags like "Yaz0", "MIO0" and the like, see if you can find, say, level textures or the title screen in your ROM using Tile Molester or whatever else. The more you can find, the higher the chance the ROM is not compressed. Alternatively, try looking through the ROM for ASCII text, be it debugging stuff, actual in-game text or whatever. If you can find at least fragments of it, interspersed with what looks like junk, the text (and in turn probably other data) might be compressed. First things that come to mind, tho maybe not all that efficient.