The conventionl wisdom is that they scream gun, and therefore should be avoided. I have used the same Eagle fanny pack since 96 when I got my piece and shield issued. The key is to wear it in appropriate settings.
When I worked in Wash. DC, there were so many tourists walking around, that it didn't appear out of place. Out in the burbs, it is more recognizeable for what it is. In the summer months, even in the burbs, alot of people wear them, so no problem.
I prefer strong side, IWB carry with an untucked shirt, jacket, etc. Belly bands have their place as well especially under a t-shirt.
At the end of the day, the mode of carrying a pistol is dictated by mission, weather, clothing, and related factors. That is why I have several modes of carry available for each gun.