You might be interested in this earlier answer I wrote about Gorbachev and his ideological influences and aims. He really was a Marxist Leninist, albeit one who had personal connections to the Prague Spring and "socialism with a human face". We'd probably say he was more of a democratic socialist.

Also of interest might be this answer of mine that details what happened with the Communist Party in the last years of the USSR and in the 1990s.

Of interest is the fact that once the constitutional monopoly on power by the Communist Party of the Soviet Union (CPSU) ended in 1990, many members began to leave: about a quarter of the over 19 million members resigned or stopped paying dues by mid 1991. The failure of the August 1991 coup against Gorbachev accelerated this process. The CPSU having its properties taken over by the Russian presidency and being outlawed on Russian territory certainly helped matters.

But: even after the CPSU was dissolved, the Communist Party of the Russian Federation (CPRF) was allowed to legally operate and form from most of the remaining local cells in 1993. It was the most popular party in the 1995 legislative elections (getting 22% of the vote). It had about 500,000" party members at the time, which was down a lot from Soviet days, but still much, much more than all other Russian party memberships combined. So clearly a significant chunk of the Party and population were true believers and not just cynically faking it.