Senior vice president David Gabriel defended the publisher against claims that it was introducing too many variants recently as it enters its Marvel NOW! initiative.
The practice of offering multiple variants is accused of artificially inflated sales of certain comic issues, as retailers purchase more copies than they require in order to acquire rare covers.
"The best barometer for that is not so much what [retailers are] saying but what they order the next time we do things of this nature," Gabriel told Comic Book Resources.
"For example... if we see a noticeable drop in those variant programmes we know they're not working. But if we see them stay at the same level or actually increase, then I know they're selling them on their end.
"They're either using them as a way to make their store more money or as a way to promote the book. That's how we know they're doing well. And it's kind of obvious, but we wouldn't be doing the programmes if they didn't work."
Gabriel admitted that interest in variant covers dropped halfway through Avenger Vs. X-Men, but that they have increased the number of Marvel NOW! variants "because it makes the most sense to be doing them".