For "internal" circuits, ie circuits where everything is contained within an enclosure that prevents any external interaction to those circuit, then it is unimportant what side of the load the switch is placed. In all cases, the operator would not be expected to have to open the unit, and any service technician would be expected to suitably isolate the supply before they opened it.
If a load is "remote" to a switch, and therefore there is a much higher chance of un-intentional or accidental interaction with the wiring to that load, then it's more usual to find the switch upstream of the load.
In the case of your cleaner, once you open the case then are potentially exposed to high voltage, unless measures have been taken to prevent contact with conductive parts at high voltage with specific shielding, potting or similar.