I'm sure what they meant by scut work is someone who is not significantly contributing to a project i.e. just comes in 2-3 days a week and does a few things here and there but can't really tell what it is contributing to because they did not have a project. Like some ugrads really dedicate long hours to research (i've known some to go into lab at midnight to check on things) and these people have projects of their own that they have done i.e. for a senior thesis or something. i.e. it is the difference of someone who is just running the gels b/c they are told to do so but know nothing of what the project is really about and may be running say a lot of gels for multiple projects but not be involved in a given project from start to finish.
Here's an example.
In the neuro lab I briefly volunteered in, you would perform these surgeries on the rat brains and do those procedures, then sacrifice the rat, take the brain and put in solution and then eventually slice the brain into histo sections which would then be stained via immunohistochemistry protocols. After that you'd put them on slides and use this counting program on the computer to look and count for what they were counting for.
To say you did all that regardless of whether you published or got the results you wanted would be to say you had your own full fledged project.
Now if you were just sitting and doing all the immunohistochemistry for all different projects whole day you'd still be helping but you'd not be having your own project to yourself. That would be scut to some people.