Damn, I just can't help responding.....GRRRR
Anyhow, to answer your question:
Think of your cellphone or wireless landline...do you get interference on it? Think of that coming through your speakers, amplified even.
To put it another way (in regards to quality): To get the signal TO the speakers wirelessly, they have to go through a transmitter (quality loss there), then they have to go through a receiver (again, another oppurtunity for quality loss) and then the signal has to be amplified in order to drive the speakers (again, another oppurtunity for quality loss).
So, you go out and buy yourself a $1000.00 ultra clean powerful amp/receiver and then negate all that quality by doing all the above.
For the amount of time it takes to run speakers indoors or out, I don't see the reason. For example: if you're running surround sound in your house, just run the wires under the carpet or pull off the quarterround and run it there.
I have heard $1000.00 boston accoustics wireless speakers and frankly, even they blew dead donkeys....