Different socialists will have differing interpretations of how socialism will distribute goods. Some say it's the same as communism: from each according to his ability, to each according to his needs. If you need more, you get more. Like for example a person in a wheelchair needs extra resources than an able-bodied person, so they will be entitled to the little extra that they need. And a woman who is pregnant is a little more fragile than other women and needs rest, so she won't have to work as hard during her pregnancy. The macro system for all of this is usually the planned economy. In a planned economy, the planners get together and come up with a giant production plan (like the Five-Year-Plans in the USSR) that says "the population needs X amount of shoes and Y amount of grain and Z amount of hospital beds" and gets to work making all that stuff. Another method is market socialism, where people believe that the workers should own the means of production, but that the market is a more efficient means of distributing products as needed. Under such a system, there would still be markets and money, but it would be a lot more equal than market capitalism because everyone would own something productive (the means of production) instead of our current system where most people are excluded from such ownership and only receive whatever pitiful wages the capitalist class sees fit to give, which often aren't enough to make a decent living.

Does a majority argue that true socialism has existed in the modern world? That I couldn't tell you. I don't have any data on the opinions of all the leftists in the world. I know that most of my leftist friends and I would answer, no, socialism has never existed in the modern world on any large scale. (On the small scale though, there are rural communes and such where people have small-scale local socialism where everyone works for the good of all and is paid equally.) But me and my friends very well could be in the minority and maybe most other leftists do think that the USSR, Cuba, China, North Korea, etc. were/are real socialism.