How much water in the blge is "normal"?

[aldo]

I've had my 23 inboard for many years and always have water in the bilge. The last owner told me he had that also, and my marina friend told me to expect that on an inboard with such a deep V. After reading Bitsamonkeys story I hope I haven't been getting too used to it.
Anyway, when I'm running the bilge pump goes off every half hour or so for a few minutes. At the dock I can expect it to go off at least once a day.
I'm looking to find out if this is normal or how to tell where the water is coming from. The shaft drips about one drop per minute as expected and I can't see water coming from any other location. I can see the inlet hose and fittings, the transducer, the plug, the shaft, and the rudder. I could not see the muffler without taking the floor out.
I have checked every visible opening after completely drying out the bilge with a wet vacuum, and still see no aparant signs of water coming in. 24 hours later I will be able to pump out at least another 5 gallons.
One suggestion was to fill the bilge with water from the inside when she's on land and check the bottom but I'm not too keen on that idea. The engine is low in the bilge.
Any thought from the experts would be appreciated!
Am I being paranoid?