I hear lots of cautions about it but until I hear an A/B example of it I won't know it when I hear it.
Anyone have such a thing?

In the most obvious version is when you have speakers that are 180 degrees out of phase by mismatching the ground on one. The sound is not clear and the direction of it is vague plus some frequencies disappear.

In a DAW it it can make the entire sound disappear due to cancellation. What often happens is poor stereo imaging. Phase as such has no sound like IM distortion or harmonic distortion. But it is a distortion.

Thanks. I feel I have a good grasp of the theory. I just don't have any examples?
IOW Theory vs experience 

washy.   Like a phaser.

@

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do as mike says and then move one clip a few samples in either direction and  then listen to the diferance

Sometimes it's not always obvious you have a phase problem. It used to be easy to check for suspected phase problems when the phase button was on the track. It's hidden in the inspector now since X1.

There are a few things that can be confusing. Sometimes you really do have a phase problems. Other times it's actually more of an issue with polarity (which is usually accompanied by minor phasing too.)

Examples of phase vs. polarity:

1. A snare drum that is miced top and bottom will almost always have a polarity issue if you don't flip polarity on the bottom mic. 
2. When micing a guitar amp with a close mic and a distance mic you're creating a time difference between the two mics, and physical distance creates differences in timing- i.e. phase. 

For phase issues it is best to visibly align timing or use a delay like the one in Channel Tools to adjust.

For polarity it is also best to visibly align timing or use a delay like the one in Channel Tools, as issues with polarity often imply small issues with phase, too. Of course, for this you will also need to flip polarity, so make sure to use that button in Sonar's mixer, then when aligning visually look for a mirror image (when one goes up the other should go down- that's what polarity means.)

Phase and polarity will sound different depending on whether you're talking mono, stereo, etc. In mono it will have less bass frequencies and sound hollow. 

Phase issues in stereo can lead to the same hollow sound but aren't as obvious.

Polarity issues with stereo (one channel has opposite polarity) will make things sound wide and doubled. Think about drum overheads. If you generally mic the drums so the snare is in the center that's where it should be. If one channel has reverse polarity the snare will sound off to one side.

It's quite a party. :-)

Peace,

Tunes

 
The main problem is: "Out-of-phase" is an incorrect description of the issue.  And has been for years.
Some idiot (prolly an advertisement guy), many years ago, used the wrong word.
The correct term is "reversed polarity." Phase is about the relationship of wavs.

FYI: There is no such thing as a polarity shifter.

references:
http://www.emusician.com/techniques/0768/its-only-a-phase/143776
Phase vs. Polarity
It might be useful at this point to quickly address a common misconception. Phase and polarity do not describe exactly the same thing. As we''ve looked at already, phase is specifically about timing. When you have a phase problem, you have a problem between the timing of two things, such as the distance between two mics or latency between two DAW tracks.
 
The term out of polarity refers to two waves that may actually be in phase (i.e., they started at the same time), but whose energy is moving in opposite directions. Polarity does, indeed, relate to the shape of a wave and how it combines with others, but a problem with polarity is not related to a time offset between two similar waves the way phase is (see Figs. 4a and b). The effects of the two are often similar: When two sounds have opposite polarity, they look and behave like two sounds that are 180 degrees out of phase. But the solutions to the two problems are different, so it can be useful to differentiate them.
 
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http://www.sweetwater.com/expert-center/techtips/d--02/14/2002
First, we need to make sure we understand the distinction between polarity and phase of signals. Polarity speaks more to how the positive and negative wires are connected. Phase speaks more to a relative TIME differential between two signals.
 
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http://totalproaudio.stevebunting.com/30/basics/phase-or-polarity/
The problem is that to invert the phase of an electrical signal simply does not make sense, and what is most commonly meant is actually a polarity inversion.
 
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This is another example of why fundamental science education should be a top priorty.  NOT math and science.  SCIENCE does not require math. And Math should not be a prerequisite for science classes.
 
Math is a tool, like pencil and paper, and crescent wrenches.
 
Science is a way of observing the universe. A sister to Art.
 
 

The easiest way to hear it is to switch the positive / negative connection to your speakers on one of the channels (left or right), then play anything through your speakers.