This is fairly subtle, but something a home inspector should check for in kitchen sinks and bathtubs with showers. There is a diverter valve, inside the faucet or the spout. This diverter valve is designed to sense a change in water pressure when the sprayer or the shower head is turned on. As the diverter shifts position, it should shut down the water coming out of the spout at the sink or the shower. Who needs a shower on, with just as much water running out the spout down by your feet? Or who needs all the water pressure coming out the spout, when you are using the sprayer? The photo below is a good example of a diverter that is not working correctly at the sink. All that water pressure coming out the spout should be diverted to the hose sprayer. Instead it is about 50/50. This situation is inconvenient and wastes water as well. Obviously, in a properly operating system, when the shower head or the sprayer is turned off, the diverter shifts positions again and re-opens the spout. If you are a repair-it-yourself type, here is a link that tells you what is going on with the faucet and how to try to remedy it. Now that you know how it is supposed to work, try it at your home. See if you have to get out the monkey wrench or not.
http://home.howstuffworks.com/how-to-do-faucet-repairs3.htm

Equal pressure. Say it ain't so!
Thanks for taking a diversion,
Steven L. Smith
Bellingham WA home inspector
www.kingofthehouse.com
Steven..............Helpful info. Now excuse me while I check it out in my own kitchen.
Duane Hosek in the Black Hills of South Dakota