In theory, socialists don't have a problem with labor. They simply do not ascribe any value to the tasks that they claim are performed by the "capitalist class". These tasks are varied, but generally include things like investment (capital allocation, speculation) and risk-taking. Since they do not believe that these tasks provide any real value (in the way that labor does), those who generate profits through these methods are therefore "stealing" from laborers who physically create goods and services.
There are many different schools of thought within the "socialist" umbrella and there is large disagreement about what should happen once the workers own the means of production. That is, once there is no more capitalist class skimming profits off the top, how do we account for the fact that certain groups of people are more productive than other groups? The problems are innumerable.
In reality, most of the "socialists" that you encounter - for example on college campuses - are socialists in name only. They don't really care about workers owning means of production or whatever. The biggest problem I've seen is that these "socialists" have a very skewed perception of the word "value". They perceive themselves to be valuable, by virtue of the fact that they exist. Therefore, anything that they produce must also have value. Should they not receive the arbitrary level of compensation to which they feel they are entitled, their frame of mind does not allow them look inward. The problem must be society!