duals udals dauls aduls uadls audls dulas udlas dluas lduas uldas ludas dalus adlus dlaus ldaus aldus ladus ualds aulds ulads luads aluds lauds duasl udasl dausl adusl uadsl audsl dusal udsal dsual sdual usdal sudal dasul adsul dsaul sdaul asdul sadul uasdl ausdl usadl suadl asudl saudl dulsa udlsa dlusa ldusa uldsa ludsa dusla udsla dsula sdula usdla sudla dlsua ldsua dslua sdlua lsdua sldua ulsda lusda uslda sulda lsuda sluda dalsu adlsu dlasu ldasu aldsu ladsu daslu adslu dsalu sdalu asdlu sadlu dlsau ldsau dslau sdlau lsdau sldau alsdu lasdu asldu saldu lsadu sladu ualsd aulsd ulasd luasd alusd lausd uasld ausld usald suald asuld sauld ulsad lusad uslad sulad lsuad sluad alsud lasud aslud salud lsaud slaud
Note: these 'words' (valid or invalid) are all the permutations of the word duals. These words are obtained by scrambling the letters in duals.