I've eaten a lot of older roos, and they have a lot more flavor than the young birds. I wouldn't call it unpleasant in any way, or strong, though. Sometimes the kidney tissue, which is the liver-ish looking tissue that can be seen on the inside of the lower back portion, (tail back, not the shoulder back) can impart a strong flavor that I don't care for. It would very likely be more pronounced in an older bird. I usually scrape that part out of the back, and rinse well, before cooking the bird. You might look for other bits that you didn't mean to leave behind, like lung tissue, between the ribs of the shoulder-back portion.
I sometimes forget to remove the oil glands on the tail, but even when I've cooked the bird without removing them, I've never noticed any change in the flavor from that. They just become two hard little oval pellets, that are easily removed. I eat the tails, too, so I'd notice if they tasted funny! Others say that it causes a bitter taste, but that has not been my experience. I suspect it may a be a myth that's just been accepted as fact and passed along. Either that or some people have a sensitivity to something there that doesn't affect me.
