I check it by feeling whether it gets hot or not
Well... with great caution! if it is working, it will get hot enough to burn you. I suppose that pitot heat for a VFR only aircraft has save a few lives over the years, probably those who have foolishly entered meteorlogical conditions they should have avoided. in more than 30 years of flying I have never chosen to use pitot heat in VFR flight unless it was a checklist item. I certainly have used it many times during flight in icing conditions.
I hold the opinion that it is installed on many light aircraft for two simple reasons: Marketing - it makes the pilot think he's flying a big plane, but more likely (in the case of Cessna) because it won't bend, and the maintainer does not have to keep aligning it with the airflow, as we had to do with the early ones, when people bent them!
As for checking the ammeter/electrical system, operating the landing light or flaps would be a better choice than the pitot heat, as each of those draw twice the current (amps) of the pitot heat. Even the flashing beakon draws more, and you can sometimes see its pulse on the ammeter.
Generally, aircraft electrical systems have a means to indicate the failure of the ammeter anyway, though there is one alternator circuit failure mode which will not trigger this indication in some C 150's, but not other Cessnas.