Further, try to abide by their requests. If they want the trash can by the door to your office or cubicle on Thursday evening, move the damn trashcan to the door. They have 100 to empty; it's a trivial task for you. We can get wound up in ourselves and forget to hold a door, or avoid spilling crumbs on our carpet, or log out of our workstation, or use a different hallway when the floor is being waxed, or to move the…
I do get being nice to janitors--and I am happy to help them with something if asked, and I don't "ignore" them as noted in this article as I definitely agree that's rude to treat them as second-class humans unworthy of being regarded with eye contact or banter--but I am being paid to do my job and they are being paid to their job and if I am spending my time or mental energy doing part of their job then I feel like something in the division of labor has failed. No one wants me spending my time working on the website or managing the social media account, and while every department certainly has something I could add to my task list to make their job easier--such as going out of my way to maintain a high-level changelog of the product or maintain a list of new translation syringe--it is their job to let me do my job, and we hired the people to do the extra work of going back through the work I did and finding those things I didn't write down at the time so I could maximize the time I spend on new development or architecture or debugging or cutting server costs or whatever it is that I was hired to do. I also think there is something to the people who argue that if you go out of your way to put away carts or use self-checkout "to help the people who work there" without realizing that you are REPLACING the people who work there--as, due to your efforts, the company can hire fewer people to do whatever that job is--then you are not actually their friend. While I avoid getting crumbs on the carpet because it is likely to attract ants or cause other forms of permanent damage to the room in the form of ground-in debris or stains, it just isn't clear to me that the most "janitor friendly" action--in the long run--wouldn't be to actively create as large of a mess as I can without people deciding I am myself such a liability that I lose my own job (and one could imagine actually conspiring with the janitorial staff over creating such elaborate "but understandable" messes ;P). Certainly, if we merely move all the trash cans to where they are most quickly gathered, the company would be almost negligent to not assign the janitor some new task to fill the time that was saved (or reduce their hours, or scale down the department, etc.).