RAW (Rules As Written), I believe the answer is Yes and No (how's that for confusing).
Detect Magic says you
"detect" magical auras, it doesn't specifically say you see them. You could possibly adjudicate that they are just felt as easily as saying they can be seen. The spell also says that the spell penetrates barriers but can be blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt blocks. So, as written, Detect Magic:
- Round 1 - allows you to know of the presence or absence of magical auras (and the general direction because of the cone shaped emanation) but not exact location, strength, number, power, or type of magic of the aura. As far as I can tell, that means objects or magical auras inside objects or concealed behind objects up to the aforementioned limitations.
- Round 2 - you can now determine the number of auras and the power of the strongest aura. Also, as far as I can tell, concealed auras as above.
- Round 3 - you can now determine strength and location of each and every aura within the cone, and if they are within your line of sight, you can make a Spellcraft check to attempt to determine the specific school of magic. This part here tells me that you can only determine school of magic if it's not concealed, meaning you can determine all of the other factors even if it is concealed.
Arcane Sight works the same way except it doesn't require conentration, doesn't have the cone shaped area (which to me means any where you can look to the range of the spell - 120 ft.), and determines all the factors that Detect Magic does except faster (pretty much all in the same round you are looking or sensing as a standard action).
Arcane Sight however does say that "You know the location and power of all magical auras
within your sight." This could be translated as you
see the auras. But then the spell goes on to distinguish factors you can determine if an object or creature is within
line of sight. I'd take the two together to mean that the first part -
"all magical auras within your sight" - means any magical aura within 120' feet of you, whether concealed or not, to the same limitations as Detect Magic, but again you can only determine school if it's in line of sight.
However, that's how I read the
Rules As Written. In my game I run things differently (houseruled). I feel that if you allow a 0-level spell (Detect Magic) to detect concealed magic items or effects, then it completely nullifies the need to search a room. I allow the caster to know that there is a magical aura in the vicinity (sense, not
see) but not be able to specifically pin-point it unless it's within line of sight (not concealed). I apply the same logic to Arcane Sight also. The advantage to Arcane Sight is not having to concentrate and not limited to a cone shaped area.
What would be really cool is if you could find (or someone else here at ENWorld) a link or a copy of any original 3.xE FAQ covering this. That could give you an "official" ruling on it. However, in my games I still go with the not seeing concealed auras, but having a general sensation that they are within the range of the spell. They still have to "search" to find them.