The ones which use a definite 8-bit encoding read/write pascal-style
strings with a 16bit length prefix.

The ones which use a definite 16-bit encoding read/write pascal-style
UTF-16 strings with a 32bit length prefix, i.e. not ByteStrings at all

The "I dunno" ones might be UTF-16 strings or 8-bit strings, depending
on the charset. Rename to ReadUniOrByteString like the other
similar horrors to flag this misery