There is nothing like unsatisfactory meditation as each meditation tell us truth about ourselves. You may sit for an hour and you are not getting anything like you wanted before you started. However you may find that that the so called bad meditation contributed somehow to the future one you would call the good one. Buddhist monks are not allowed to talk about their meditations however I spoke to one monk and he revealed to me that some his fellow monks had terrible meditations. It is as though the monks are supposed to have great meditations just merely because they are monks which means proffesionals. Sometimes you may have so called bad meditations in a row. However once in future you may sit and immediately you know that you getting there. So it I better not to be too sceptical. Meditaion may be affected by a number of reasons. You may not feel well physically . Perhaps you had a bad day or something. So it is better not to put too much stress on yourself.