Isn't that what everybody does? It's rare to see a boat not plugged in when in a slip.
At least where I cruise, the boats are constantly pumping-out fridge/freezer cooling water. Some boats have airconditioning with a dehumidifier setting -- they turn on periodically just to keep the humidity down.
Most people that have shorepower leave their battery charger on all the time. Most modern chargers that you would want on your boat are multistage chargers that charge the batteries only as needed. This is the kind of charger that you want.
As with all questions, it depends. There are two major factors, the charger and quality of electric on the dock. If both are good you should be good. It does help prevent a bilge pump from running the batteries dead. But it can aggravate galvanic corrosion if the boat's wiring or dock wiring has issues.