A few things:
I'll agree with Roger about thieves stealing cameras. A camera is a camera, some thieves may know the difference between a digital and a film camera but we all know that most thieves are idiots. Case in point: When my apartment in Jersey City was burgled, the perpetrator/s stole my Lowepro bag with 2 Nikon DSLRs, 3 lenses and some cards, then opened my dirty old Domke to reveal a Leica M4 with DR Cron as well as a Nikon SP with 5cm f/1.4 Nikkor. The thief left the old film cameras although each was worth more than the gear they stole. Meanwhile, they went into my housemate's room and stole her K1000 with 50mm f/1.4, a camera she was given and had sentimental value but would sell for $20 at a thrift store. Note: Both the Nikon DSLRs had the logo painted over in black. it did not render them invisible. Perhaps I should have used tape. I wonder if gaff tape has more invisibility power than electrical...
As for stealing expensive lenses vs. crappy lenses, I doubt there is any real case for it. The thief would probably steal any lens if they are going to be that bold. Show them a well used Noct-Nikkor against a pretty 55mm f/1.2 and they'll choose the shiny, not the user that is worth 10+ times more. It's all perception.
As for the taping itself, some logos look ugly or ostentatious. The big red dot on the Leica M4-P comes to mind. Then again, it's usually covered by a hand. I think the nicest logo is the simple "Nikon" on the front of the F2. I like the old "Canon" on older film bodies.
Really, if a working photographer doesn't want to advertise for their marque or isn't sponsored by them or the broadcaster doesn't want to feature it; it may be advantageous to tape over the logo. This is why we see that at sporting events, etc.
Phil Forrest