Is always good to have a curious mind, because it keeps you young :bsmilie:
It depends on situation and location. If you are shooting indoor, it is okay to shoot without filter.
The picture quality difference is almost non visible if you use a good filter.
If shooting outdoor, especially in a dusty environment, a filter will keep your front element clean, so you do not need
to clean it. It is best to avoid cleaning the front element, some people will say it will damage your lens coating. My own opinion is
the coating will not be so easily damage, if you use the proper method and be careful.
Only, one kind of shoot, I will confirm remove my lens filter. That is shooting sunrise or sunset direct.
Removing the filter may help to reduce the flare. But again is subjective. Some people love the flare and it makes the picture more interesting.