Sometimes when downloading a Macintosh file using the XMODEM file transfer tool, the file refuses to transfer in the MacBinary mode and uses Straight XMODEM instead.
If this happens, it's probably because the file header is corrupt or the file was uploaded improperly. Most likely the BBS from which you are downloading is DOS Based. The reason that the the transfer switches to straight XMODEM is that a file can only be downloaded as a MacBinary file if the transfer protocol recognizes a proper Mac Header (file type and creator).
If you download the file anyway, you may be able to open the resulting generic file with a word processor, but the file is probably not a text file. What is downloaded is a generic file, which results in non-printable characters to be filtered out when opened with a text processor.
Instead, try just using straight XMODEM and then use some utility that allows changing of the file type and creator (such as ResEdit or Disktop) and set it properly. If you cannot find out the proper file type/creator, then the file will have to be reuploaded properly or you will not be able to use it.