The Blues led through a stunning 29th-minute strike from top-scorer James Alabi until referee Martin Coy handed Guiseley a way back into the contest.
Seven minutes into the second half Connor Brown went down in the box under a challenge from Johnny Hunt who insisted he had not touched the Lions right-back.
But Coy pointed to the spot and Shane Walton beat Alex Lynch from 12 yards to restore parity and ultimately earn Guiseley a share of the spoils.
And the man in the middle further infuriated the Blues in the 67th minute when he waived away Craig Mahon's appeals for a penalty at the other end after he was seemingly pushed in the area by Brown.
It is believed Coy had second thoughts about his spot-kick decisions and that he apologised to McCarthy after the match for awarding the first.
The Blues boss chose not to criticise the officials.
But he added: "Their management team did put the officials and the fourth official under a lot of pressure. That's not my style.
"It's doesn't mean my style is right and their style is wrong, going right up the tunnel, but it might be something I have to pretend to do to get on at officials and put it in their minds.
"But having said that, he's a good referee, and I'm sure he wasn't influenced, but I can tell by the reaction of all of our players, and by the their players, that I'm 99% certain that wasn't a penalty (for the foul by Hunt).
"It's done now and I can't do anything about it, even if it is wrong, but it's a blow for all of our fans, who have come here looking for another three points."