Raiders had won five successive National 2 South games heading into the match but the defeat leaves their hopes of a top-two finish dangling by a thread.
Worthing dropped a place to sixth in the table and trail second-placed Dorking, who have a game in hand, by 12 points and are 17 points behind leaders Henley Hawks.
Dawson said: “It was very disappointing and we just didn’t get off the bus.
“We’d come so far in the last few weeks but just regressed eight weeks on Saturday as we just didn’t play.
“The pitch was a big leveller but it was the same old story for us. They scored a couple of tries from driven line-outs, including a penalty try.”
Raiders trailed 13-5 at half-time, before fighting back to lead 17-16 with 20 minutes to play.
Raiders then had Charlie McGowan sinbinned and Dawson said: “We went into the lead but Charlie was then sent to the sinbin.
“It seemed pretty harsh as the referee interpreted that he had brought down a line-out and they were then awarded a penalty try. We felt what Charlie had done was legal, so that was disappointing.
“The over-riding feeling at the end of the game was disappointment. The lads had worked so hard to get us into a great position and with a fighting chance but now it looks like it’s slipped away.”
Taunton went ahead after just two minutes when they drove forward for Ben Turner to touch down and Gary Kingdom added the extras.
Raiders responded straight away as good hands from Scott Barlow saw Jamie Redmayne break through. His offload was superbly picked up by Elliot Luke, who fed Kieran Leeming and he flicked the ball through his legs to release Ben Loosmore. His outside break and fend was too much for his opposite number and he drew the last man to send Matt McLean galloping in from 20 metres out.
Two penalties from Kingdom saw Taunton take a 13-5 lead into half-time.
Almost straight from the restart, Kingdom kicked over another penalty to give the hosts a 16-5 lead.
Taunton had Turner sinbinned shortly afterwards and Raiders made the man advantage count when Finlay Coxon-Smith burst past several players to go over and Craig Marchant converted.
Raiders soon went ahead as Alex Nielsen managed to ground the ball, with the try awarded after the referee consulted with the touch judge.
Marchant missed the conversion but Worthing led 17-16 with 20 minutes to play.
Taunton pressed forward and were awarded a penalty try, with McGowan yellow-carded as well. Kingdom’s conversion put the hosts 23-17 ahead.
Raiders pushed hard for a way forward but a loose pass saw them back on their own line. After a number of phases, Lewis Webb went over and Kingdom’s conversion hit a post and dropped in.
Worthing entertain Lydney on Saturday (2pm).
RAIDERS: McLean, Marchant, Loosmore, Coxon-Smith, Nielsen, Leeming, Peach; Smith, Hewick, Redmayne, Barlow, McGowan, Sargent, Luke, Storer. Subs: Walker, Miles, South, P.Burns, Dudley.