I, too, have lots of these. Sometimes there is a clue in the middle name. But let's face it, in those days there really was no means of knowing the paternity of your child unless.....well, you know. And even if there was a bastardy order made, it doesn't necessarily follow that the subject of the bastardy order was indeed really the father.
When I first started doing genealogy, I was quite shocked by the amazing number of children born out of wedlock, with unknown fathers. But I read later that illegitimacy was very common and it was the Victorians who demonised it and made it unacceptable. This was purely a pecuniary decision, as single women were far less able to support a child, than a father with a job, and a mother to do the child rearing while simultaneously running the house and probably also taking in washing or doing cleaning or something, so the parish often had to take on the expense for these children.
Linda