Code Assist insists on putting double quotation marks around column names when selecting them (and when autoselecting them for you):
which of course makes Code Assist more a roadblock than useful, since it means more work removing the quotation marks than writing the statement blind.
The issue seems to exist in the last three beta versions of 18.104.22.168 (currently using the one expiring Dec 30th).
![2015-12-01 08_08_57-Toad for Oracle (x64) BETA expires on 30-Dezember-2015 - TLS@TLS.WORLD - Edito.png|690x419