Hi Neil,
some cameras do have good mics, as my HF M40 & 41, but the issue here (I think) is having a mic that is more than just a few feet away and you get "hollow" sound. Unforgivable result.
As for using a mic attached to the camera, if using 1/8 in mini-jacks, which is all I ever use or can afford, the cabling might not be properly shielded, though that's not occurred with me, yet.
I actually have a wireless lavaliere as one of my mics, I put the mic transmitter in a pocket, and plug the receiver into my camera, sounds darn good for a sub-$200 setup, and I can be mobile.
I might add the lavaliere clipped to my shirt looks very "Pro" onscreen. In addition I can plug any of my mics into the transmitter, including my Zoom, I don't have to use the lavaliere.
Imperfect video? People may still watch. Lousy audio? People will usually click away much faster.
HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)
Nvidia GTX 960(4GB)/16GB DDR3/
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5.
Tape capture using 6 VCR, TBC-1000, Elite BVP4+, Sony D8 camcorder with TBC.
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