Blades boss Bryan Robson saw his side booed off the field with further chants of 'Robson Out!' amid rumours that the manager is just one game away from receiving the bullet.
United took the lead via old faithful James Beattie but Blackpool clawed their back into the game and equalised through former Bradford City midfielder Claus Jorgensen.
Beattie netted in the 23rd minute but the home side failed to stick away opportunities to kill the game when they spurned chances after chance after chance.
Blackpool had come into the game on back of a 4-0 victory over Coventry City and paved their first chance of the day within three minutes - Gary Taylor-Fletcher volleying over the bar from 15 yards.
In the ninth minute the home side could have opened the scoring but failed to do so when Beattie, chasing his 13th goal of the campaign hit his penalty straight at the keeper.
The spot kick was originally awarded when Billy Sharp was pulled down in the area by Ian Evatt, who for his troubles was red carded.
But minutes later the former Everton forward made amends when Sharp crossed in from the left with Beattie handed a simple header six yards from goal, 1-0.
Straight from the restart the Seasiders were almost on level terms, Ben Burgess far range shot rattling the bar of Paddy Kenny's goal.
After a collision with Blackpool keeper Paul Rachuba striker Beattie was forced to leave the field through injury - with Rob Hulse making his long awaited return.
From then on opportunities for United grew and grew but the home side failed to take advantage of poor Blackpool defending, Chris Armstrong spurning three chances in space of ten minutes.
Keith Gillespie kit a low strike straight at Hulse as they got in each others way before Armstrong smashed the ball over the top after great play by Sharp. Armstrong then hit a smash shot over the bar from 20 yards and Gillespie failed to hit the net.
On 68th minute Blackpool were awarded a needless free-kick with Claus Jorgensen seeing his shot take a deflection and past keeper Kenny.
It was a frustrating day for the Red and White Wizards which on reflection should have won this game after the visitors were reduced to ten men.