Face and chase should be in the $20-$30 range. If it isn't then buy the tools yourself, learn how to use them and then face and chase 10 of your friend's bikes for $20-$30 and make back your investment.

Should it be done? Yes.
Just for new installations? No.
Does it "have" to be done? Mostly not.
Can it be done more than once? Yes, but pay attention to your overall BB shell width...most BB's have a minimum acceptable BB shell width.
Does it need to be done for older self-contained systems, or just the new external bearing type BBs? Both, although I have seen sealed BBs work just fine in shells that were so bad that when swapped to external bearing type BB and crank the spindles bound solid and couldn't complete a revolution.
Can it be done with a file (the facing)? Yes. I've done it that way before. Then again I used to be a locksmith and have hand cut keys with a file before....Get some Dykum and pay attention to what you're doing.

As Dave Moulton has pointed out, lack of sightable exposure does not prevent rust (hence bolts rusting inside nut threads). It's a spurious argument.

A new modern bike frame does not need facing with the array of sealed BB cartridges which are available and which don't need accurately perpendicular shell faces to do their job. The external bearing jobs? Well they might be a different story.

BB facing arises from the need to enable smooth running of bearings and spindle in traditional-style BBs. There is only one identifiable symptom indicating a shell needs facing for this style of ball-and-race BB -- a tight/loose pattern when the spindle is turned and the bearings have been properly adjusted.

Several shops I have worked in faced everything over $400, and some did EVERYTHING. Facing is one of those details that set a shop apart from the herd, like building wheels.

And there are plenty of bike shops that build wheels and shouldn't.

I was giving my new Giant TCR C-2 her first cleaning, and notice maybe a "firm spot" while rotating the crank. It did seem to spin easier after a couple of revolutions, but it seems to me that my other bike's crank spun with much less resistance when the chain was off the bike. The Giant spec is a Race Face Cadence BB and crank. My LBS had to swap out the BB and crank as the frame that I bought is the Limited frame, but the bike was built to the C-2 spec. Should I have LBS look at it?

How can you assure a perfect 90 degree angle on both sides with a file? Yes, a file might bring down a high spot, but maintaining a perfect 90 degree angle requires the special tool. Go to Park Tool's site for an explanation on chasing and facing.

"Perfect 90 degree"???

If you mean, "how do you keep the shell faces parallel to each other?" Then yes you would have a point....doing it with a file will not achieve perfectly parallel faces, but in good hands the file will be able to put the faces close enough (in parallel) for any noticeable binding to be eliminated.

Actually, 90 degrees to the plane of the spindle. The shell faces may be parallel, but not at right angles to the spindle. But agreed that a file wouldn't do the job without a large degree of patience and checking. That is, if the facing was ever needed in the first place (which is rarely if ever is if a cartridge BB is to be used).

The ideal situation is to have the faces parallel to each other and at 90 degrees to the threads. Cartridge type bottom brackets would probably be more forgiving, but the chase and face process pretty much assures a good tight, creak free fit.

The ideal situation is to have the faces parallel to each other and at 90 degrees to the threads. Cartridge type bottom brackets would probably be more forgiving, but the chase and face process pretty much assures a good tight, creak free fit.