Russian F1 commentator Alexei Popov is quoted by Basler Zeitung newspaper: "I had to read the (press release) several times before I could believe it."
Some of the sport's sceptics are still not sure.
There are reports of links to the KGB, but in truth very little is known about the entities listed in the Sauber release.
The likely debut of a 17-year-old Russian driver next year is also highly unusual.
"First of all I want to wish Sergey (Sirotkin) and his associates good luck," said Oksana Kosachenko, the former manager of ex-F1 driver Vitaly Petrov.
"But so far, he is not a Formula One driver. This is about certain arrangements which, undoubtedly, will be implemented."
Germany's Bild newspaper, however, claims that "not a cent" has yet flowed from Russia to Hinwil.
But a team boss who has worked with Sirotkin and his Russian partners before, Andreas Jenzer, told the Tages-Anzeiger newspaper that his dealings were all positive.
"When I first came into contact with his Russian supporters in 2008, I also had a little bit of concern initially.
"But I've never had a bad experience in all of the years," Jenzer said.
It seems that much will depend on whether Sirotkin makes his race debut next year, based on a series of track tests that could include appearances on Friday mornings in 2013.
But German broadcaster Christian Danner warned: "Unfortunately he is light years from the levels of a current Formula One driver."
Red Bull's Dr Helmut Marko knows more about the pecking order in Sirotkin's current race series, Formula Renault 3.5.
"Sergey is currently in the midfield, and he has struck me as not bad. Better than (2013 Sauber driver Esteban) Gutierrez.
"But he will have to show what he can do under pressure."
A major hurdle for Sirotkin will be getting his mandatory FIA super license, as Marko insisted: "You can't just get your sponsors to buy it for you!"
Some suspect the Russian deal was one done out of desperation by the financially-dying Sauber.
A Swiss supplier to the struggling F1 team told Aargauer Zeitung newspaper that his company has not been paid a cent by Sauber since December of last year.
A Swiss media source told us: "Unfortunately, Sauber has to play the game (with the Russians), but it's better than shutting up shop."
Speed Week also thinks the Russian deal is a good one, because it's "only a matter of time before normal sponsorships flow from Russia, with Gazprom in pole position".
Bernie Ecclestone, meanwhile, hailed the Sauber deal, and also Tuesday's news that the backmarker Marussia has inked a long-term engine deal with Ferrari.
"I'm glad that Sauber and Marussia are continuing," the F1 chief executive told Blick newspaper.
"But how serious the situation really was with these teams, I don't know."
Ecclestone added that Russian president Vladimir Putin is supportive of the Sauber deal.
"I was with him in Moscow three times," said the 82-year-old. "He is very enthusiastic and helpful, which will benefit the whole of F1."