The answer to that questions is very much up to the individual circumstance. For instance, if you have a basement that is not finished, not really much down there besides maybe the heating unit, and there is typical looking moisture like we see in the picture here, then it is likely not serious. In fact, that is typical of many areas. There is no such thing as a 100% dry basement.
But now if you have a finished basement with that same moisture, your family is down there a lot, and it is where you store your clothes and other items, that may be unacceptable.
Most basement moisture can be easily controlled with gutters, slight improvement to grading, and a couple of dehumidifiers. Basements with a more serious issue may require more serious work.