Ricardo Fuller had a chance in the opening moments for the home side but his header was saved by Manuel Almunia.
Deeny was again denied by Gilks minutes later as he saw his penalty saved by the keeper after Almen Abdi was brought down by Neal Bishop.
Watford's keeper came to his side's rescue yet again when he denied Gabriele Angella after a free kick had fallen to the Blackpool defender.
In the final five minutes of the half the visitors struck the woodwork twice. Lewis McGugan headed an effort of the bar from an Abdi corner and moments later Diego Fabbrini fired a shot off the post.
Substitute Ince made his return to the team and within moments of being on the pitch he fired a shot just wide of the post.
Blackpool were taking the game to Watford and Barry Ferguson forced Almunia to tip his free kick over the bar.
As the game entered the final 10 minutes, Ince finally broke the deadlock when he fired in a shot into the bottom corner after a fine run that gave his side the victory.