I spent 4 years loading a topdressing plane while doing my PPL and then onto CPL training. It was the best apprenticeship one could have leading into commercial flying. It gave me a good grounding in aviation, with things like refuelling, safety around aircraft, in the field maintenance issues, bulk fuel ordering and handling, to an exposure to the weird and wonderful hours that pilots encounter. Not only that, I got to see a lot of the countryside other people never get to see.
Riding around on the ferry flights in the cockpit of the plane I had a boss with 20,000 hours and I learned more about strip flying, mountain flying, and bad weather flying than any of the training I did at the aero club or the flight school I went to for CPL.
The $82 per production hour we got paid wasnt all bad either just quietly.
Throwing bags into the back of a 737 or emptying the sewerage tanks might be a job at an airport, but its not going to teach you a great deal about flying planes, especially small ones.