It's true that tiredness is a very common complaint but if it really bothers the person enough that they've come for a visit I'd still do some basic screening even if the person appears healthy. There are enough people with non-existent problems who frequent clinics several times a year that you going for a visit for the first time are unlikely to be put in the whiner category.

Even here in Finland where we have long dark winters and we have mostly national health care that is trying to be cost effective tiredness is a good enough reason to go visit a doctor.