Motherwell manager Stephen Robinson lambasted his side's defending as they were hammered 7-1 by Rangers on Sunday.
But Robinson refused to use the sending-off as an excuse for their capitulation.
"We looked like we had an excuse in the bag," he said.
"The decision changes a big aspect of the game but the manner of the defeat was really disappointing.
"It was woeful defending and people need to look long and hard at themselves.
"I thought it was a penalty and the letter of the law suggests that he (Carl McHugh) needs to be sent off.
"The first booking is a disgrace, it's embarrassing. And I have to say, referees are getting conned by the same people continually.
"Certain players get away with certain things every week. They (referees) have a hard task.
"If you are getting fooled every week all the time then it's difficult for them. It wasn't a free-kick in the first place, it certainly wasn't a yellow card."
Celtic boss Brendan Rodgers also had a gripe with the officilas as he believed Livingston striker Dolly Menga should have been sent off in the goalless Ladbrokes Premiership encounter at the Tony Macaroni Arena.
Menga appeared to move his head towards Ryan Christie as they jostled while waiting for a set-piece but although referee Kevin Clancy interjected he took no action.
The point took the Parkhead side top of the Ladbrokes Premiership on goal difference over Hearts.
Afterwards Rodgers, who revealed defender Kristoffer Ajer will need surgery on an eye socket injury sustained in the second half, said: "He should have been sent off. I thought so in real time.
"I thought he gestured his head towards Ryan and when I saw it after the game it was actually more aggressive than I thought and he was very, very lucky to stay on the pitch.
"If he goes down it doesn't matter if the referee hasn't seen it. I assume he hasn't seen it so if he goes down or not it doesn't matter.
"It wasn't a great action by the player so you can only assume all the officials haven't seen it."
St Mirren boss Oran Kearney bemoaned his side's inability to stamp home their authority after edging in front in the basement battle at Dundee.
But the Northern Irishman did feel the Buddies should have had second crucial spot-kick late on when substitute Danny Mullen hit the deck.
He said: "For 25 minutes after we scored we got the wrong reaction. They got the reaction I wanted from us.
"Rabbit in the headlights possibly, 'what's happened here?', that type of thing.
"We should have had a second penalty. I have watched it again and we should. "It would have been a lovely way to end the game.
"Kyle clips a free-kick in, the header comes back across and it is like the first one, Danny is between the full-back and the goal, he is on the six-yard line about to drill the ball and as he swings there is contact made, enough for Danny not to touch the ball."
St Johnstone moved up to fourth following their 4-0 thumping of Hamilton.
The game marked another clean sheet for keeper Zander Clark, his fifth in a row, and boss Tommy Wright cannot believe he not been called up to the Scotland squad.
He said: “First of all I’m devastated for Zander, it’s a decision which beggars belief really.
“When we saw he’d been overlooked everyone was gobsmacked.
“That’s taking nothing away from Jamie MacDonald, who is a very good keeper and someone I have tried to sign in the past.
“But on form, Zander has been outstanding.
“He’s had five clean sheets in a row and even though we got beat from Celtic in those games, he was excellent.
“I know people will be thinking it’s the big daft Northern Irishman coming out and sticking up for his player again, but I just can’t believe it."
Neil Lennon meanwhile is concerned by Hibernian's dip in form as they dropped to seventh following their 1-0 defeat at Aberdeen.
They have now failed to win since the 6-0 thumping of Hamilton on 6 October and have failed to score against Hearts, St Johnstone and Aberdeen.
"There is a little dip in form," Lennon said.
"It is something we're not used to, but you have to accept it is not going to be on an upward trajectory all the time.
"I don't know if we are lacking a bit of confidence or decision-making is not right. That's three games when we haven't scored and we have missed good chances in all of those games."