Key also admitted on Tuesday that England had "mucked up" again with their performance in a major Test series.
England's disastrous tour, where they have lost the Ashes series in just 11 days of play, has left the ECB managing director of men's cricket with plenty of tough questions to answer.
He was supposed to have an all-in media conference in Melbourne on Tuesday ahead of the Boxing Day Test, but there was a late change and Key spoke to English journalists only.
One of Key's most pressing concerns involves the issue of alcohol consumption.
The squad visited Noosa between the second and third Tests, a long-planned part of the itinerary designed to help players relax and unwind on a long, intense trip.
A host of TV crews, photographers and reporters followed them to the coast and some of the coverage has focused on the amount of time some individuals spent in bars.
Key, who did not join the group in Noosa, insisted he had no problem with the break, but would not be happy if he found evidence of over-indulging.
"If there's things where people are saying that our players went out and drank excessively, then of course we'll be looking into that," he said.
"Drinking excessive amounts of alcohol for an international cricket team is not something that I'd expect to see at any stage and it would be a fault not to look into what happened there. From everything that I've heard so far, they actually were pretty well behaved. Very well behaved.
"We've got enough ways of finding out exactly what happened and everything that I've heard so far that they sat down, had lunch, had dinner, didn't go out late, all of that, had the odd drink. I don't mind that. If it goes past that, then that's an issue as far as I'm concerned.
"I have no issue with the Noosa trip if it was to get away and just throw your phone away, down tools, go on the beach, all of that stuff. If it goes into where they're drinking lots and it's a stag do, all of that type of stuff, that's completely unacceptable. I'm not a drinker, I think a drinking culture doesn't help anyone in any stretch whatsoever."
Key also revealed he had previously looked into reports players had been spotted drinking the night before a match in New Zealand, just before the Ashes.
A short clip of white-ball captain Harry Brook and Jacob Bethell was shared by a member of the public on social media, said to have been taken while they were out in Wellington.
"I didn't feel like that was worthy of formal warnings, but it was probably worthy of informal ones," he said.
"I think that was a bit of a wake-up call actually for what they're going into."
Also on Tuesday, Australian coach Andrew McDonald said he trusted his players to be ready for Boxing Day after their celebrations, having secured the Ashes on Sunday in Adelaide.
"There's always concern for Head," he joked about Travis Head, who celebrated hard.
"They've earned that, they're responsible adults.
"They always strike that balance, there are no instructions from me around that.
"They'll be ready to go come Boxing Day morning. I don't think there will be any hangover - maybe yesterday there was a hangover, and maybe today, I'm not sure."
McDonald added Australia were "a changeroom full of adults."
"They make choices - sometimes they make mistakes and I'm not saying Heady has made a mistake in this instance," he said.
"Have they (England) been drinking? I'm sure they might have a beer or two, here or there, and they're entitled to do that as adults."
Key also backed Brendon McCullum, calling him "a bloody good coach", but said it was up to the ECB what happens in the wake of this tour.
"Clearly, we've mucked up on the big occasions, whether that was the home Ashes series, whether that was last summer against India," he said.
"The big ones have eluded us ... we have to evolve. We have to make sure that we're doing things better."
McDonald said some English tactics had caught Australia unawares.
"We have been a little bit surprised at times, with the way we had seen them play, to what they've delivered at certain times," he said.
"That's their problem, not ours."
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