Silicon Valley venture capitalist Peter Thiel is famously outspoken and sharp-tongued, and on CNBC on Wednesday he did not disappoint.
"Twitter is hard to evaluate. They have a lot of potential. It's a horribly mismanaged company—probably a lot of pot-smoking going on there. But it's such a solid franchise it may even work with all that," the co-founder of PayPal and early Facebook investor said.
But Thiel said he would not call for the ouster of Twitter CEO Dick Costolo.
"I'm not sure they could do that much better. The CEO can't really change things that much in these companies. You'd have to fire everybody and start over."
Thiel, who does not own shares of Twitter, said the founders of the social media site set the tone for the company's culture and it's hard to change.
"One of the paradoxes is when you have a business model as good as Twitter—where you have 140 characters, no one can copy it, no one can compete—you can be screwing a lot of other stuff," he said.
"The management can be B plus. Maybe some people come in at 10:30 and leave at 5 p.m.," he said. "It feels like it's vastly underperforming its potential."
Twitter did not have any immediate response but one early Twitter investor did—in a tweet.
Asked if he were to invest a dollar in either company, Thiel said he'd "probably still go with Google" despite the antitrust concerns from European regulators.
The European Commission is pushing Google to make adjustments in its settlement over demands that the company make additional changes to its search algorithm.
"The risk with Google is the EU antitrust stuff," Thiel said.
"Silicon Valley is sort of fairly oblivious to how this [antitrust issue] is building up because there's been very little scrutiny from the U.S. on Silicon Valley," he continued. "The EU is quite hostile. It's in part because European companies have not been able to compete on the IT sector. So they are running to the regulators to shut down the U.S. businesses."
The risk with Apple would be that the company, at some point, might lose the pricing power on smartphones, Thiel said, adding the tech giant's newly announced mobile payments system and the Apple Watch are not enough to make a difference to the company's bottom line. "If you have $150 billion coming from phone revenues, it's really hard to have product lines that even come close to moving the dial."
"Even the iPad wasn't enough to move the dial," he said.
"Maybe if they reinvent television sets, which is a thing they've been talking about for a long time, that might be a vertical that would be big enough," Thiel said.
Never one to mince any words, Thiel also took the car-sharing service Uber to task—notwithstanding the fact that he invests in its closest competitor Lyft.
Uber is the most "ethically challenged" company in Silicon Valley, Thiel said.
"We do not invest in Uber. ... We do not look at it," Thiel, co-founder of PayPal and Palantir, said. When asked why he didn't invest in Uber, Thiel said he "missed the boat early on" and now the ride-sharing company's valuation has gotten "too high for our liking."
Thiel, author of the new book "Zero to One," questioned the intensity of Uber's competitiveness.
"There's always a question, you know, how intensely you're allowed to compete, and Uber is right on the line," Thiel said, although he added that the company will likely "get away with it."
Uber did not immediately respond to a CNBC request for comment.
Thiel, one of the most prominent openly gay men in Silicon Valley, also took a philosophical view on the question of gay chief executives.
"I suspect there probably are a number of gay CEOs who haven't announced it," Thiel said. "I suspect its mostly a generational thing."
Thiel said gay CEOs who are in their 50s and 60s are unlikely at this point to reveal their orientation publicly, but that things will change over time.
"I think we'll be seeing a lot more in the decades ahead," he said.
—By CNBC's Matthew J. Belvedere. Hailey Lee contributed to this report.