"You can't pay the same price for something that is much worse than they claimed," he said at a conference in Miami.
Musk, who on Friday said his $44 billion deal to buy Twitter was on hold pending information on spam accounts, said that he suspects they make up at least 20% of users - compared to Twitter's official estimates of 5%.
When asked at the conference whether the Twitter deal is viable at a different price, Musk responded, "I mean, it's not out of the question."
"The more questions I ask, the more my concerns grow," he said at the All-In Summit 2022 conference.
"They claim that they've got this complex methodology that only they can understand ... It can't be some deep mystery that is, like, more complex than the human soul or something like that."
Twitter shares extended losses in late afternoon trading following Musk's comments.
The stock dropped more than 8% to close at $37.39, lower than its level the day before Musk revealed his Twitter stake in early April, sowing doubts that the billionaire entrepreneur would proceed with his acquisition of the company at the agreed price.
Twitter Chief Executive Officer Parag Agrawal tweeted earlier on Monday that internal estimates of spam accounts on the social media platform for the last four quarters were "well under 5%," responding to days of criticism by Musk of the company's handling of phony accounts.
