"I am angry and I hope the players are too," he said.
"This was a game we should not have lost.
"But we have players who were too selfish at times and you don't win anything as a team when that happens.
"I honestly believe we have a squad that is good enough to be sitting in the middle of the table in the Championship.
"But we are where we are. It's no good just producing performances two or three times out of every six or seven games.
"I get paid by the chairman who works four weeks a month and so do the players.
"We have got to put together a consistent run of form and that has got to stretch over a number of games."
Coleman was left angered by a couple of glaring misses early in the game by his side.
Striker Leon Best should have done much better when he fired in a poor effort from an angle that goalkeeper Joe Murphy saved.
Best's strike colleague Clinton Morrison was waiting unmarked in the middle for what would have been a simple tap home.
And Best failed to find the net again a couple of minutes later when he broke free into the box, denied a second attempt by Murphy who was then stretchered off with a knee injury after colliding with a post.
Both efforts took place before Scunthorpe, without a win in the previous five games, got the only goal of the game after 30 minutes.
Leading marksman Gary Hooper raced free from the halfway line to produce a clinical finish past keeper Kieren Westwood for his seventh goal of the season, but the first in nine games.
In the second half Paul Hayes came close to adding to Scunthorpe's score but in the closing minutes substitute Gary Madine missed a great chance of an equaliser for the visitors.
Scunthorpe manager Nigel Adkins was delighted with the three points.
"It was a big win for us but then our home form has been good this season," he said.
"It was an excellent goal by Hooper and even more pleasing because it was from a move we have worked hard on at the training ground this week.
"I have great faith in Gary Hooper and Paul Hayes as our strike partnership up front and Hayes was so unlucky not to get on to the score sheet himself in the second half.
"We are a team that likes to try and play good football but sometimes that is not always possible particularly on the winter pitches.
"There was a deluge of rain before the game which made it difficult to pass the ball around as quickly as we would have liked.
"Coventry caused us one or two hairy moments in the first half but we also caused them a few as well at the opposite end and I think we deserved our victory."
The win lifts Scunthorpe up into 17th place in the table putting a four-point gap between themselves and the relegation places.