Yup, they can leave a mess. I got my first satellite dish in the mid 1990s (Dish Network). Back then you could buy the whole system as a homeowner-installed kit and I installed it myself, being careful with the shingles, cabling, etc. I took my time - added extra blocking in the attic, ran the coax neatly outside and inside, carefully sealed all building penetrations, etc.
Time went on and many years later I switched to DirectTV. I was told that homeowner-installation was a thing of the past and that they had to have their official installer mount it up. I don't like people stomping around on my roof so I met the guy when he arrived and persuaded him to let me install it (he honestly didn't care either way). It was really simple to install because of all the careful work I'd done the first time.
I no longer subscribe to either service, and when I re-roof in the next few years I'll remove the dish for good.
