I banged my head against it for a while and found that it's only a problem when using a custom template under View Results. The standard template decrypts the data beautifully.
So now I'm using the standard template, but since it was displaying everything in one very long and very narrow column, I changed line 183 in ViewFormResults.ascx from
< TD align="left" width="144" >
to
< TD align="left" width="800" >
It's not the most elegant solution (one column of field names and another of field results would be easier to read) but it works.