Whenever I try to use natural harmonics on the 5th fret, I can barely hear them on the low e, a, d, and g strings. On the b and high e, you can't even hear them. Why can't I hear them? Is it intonation issues or something? I can hear them just fine on like the 7th or the 12th.
The 7th and 12th fret harmonics are usually the easiest to hear, from what I've been told. I don't exactly know what the issue would be, but I've found it easier to hear on some guitars, than on others. I'm not sure if its a matter of intonation or another construction issue though.
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It can be because of your technique. The correct way is to just hold your finger gently on the string and then after plucking it, lift it off. Don't pluck too hard though. You should get a sound even if your intonation is screwed up.
/\ what that guy said... also a good little trick is to pluck the string nearer the bridge (not too far towards or you'll loose tone), and this helps bring out the harmonic...
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You can't hear them because you aren't hitting them correctly. Just keep practicing and they will come.
Try starting at the 4th fret, and slowly sliding your finger up towards the 6th fret. My understanding of guitars tell me intonation shouldn't effect your ability to produce this harmonic because it's not actually using the frets at all it's just dividing the string up however there could be some sort of resonance problem with the guitar.