In my opinion, if all the dogs are getting everything they need (including training, affection, exercise), then you don't have too many lol. This also means that you aren't putting yourself in a financially disastrous situation.
My uncle used to get looks like he was insane for having 11 dogs. He owns a 20 acre farm, and is VERY well-off financially. No children. The dogs work the farm and are his companions. All of them get everything they need/want. So for him, not too many dogs. My limit personally? Three. LOL!
Mom To~ Dakoda (b/t GSD), Simi (b/w DSH), Nashoba (sable GSD)