I just filmed with a wireless lav. While I was recording I herd an intermittent hiss and rasp sound but couldn't figure out the cause. Reviewing the footage afterwards I think the movement of the excess wire between the mic and body pack was the culprit since the mic was properly clipped to his lapel and wasn't rubbing up anything. The sound coincides with his movement, for example stretching out his arms.

I've also noticed the wire rubber is starting to become less flexible with age. Note its decent quality Audio-Technica wireless lav thats about 7 years old.

1. How do you secure lav wire while giving enough play for the subject's movement?

2. What do you do when the wire gets rigid due to age?

Here is a link about Lav micing that might help....
Location Sound Corp. -- Tech Tips (http://www.locationsound.com/proaudio/ls/tips/techtips8_4.html)

Thanks Brian that link was very helpful. Sometimes you think you know it until the situation changes. I use wired lavs every day and haven't had a problem but the subjects are seated at a table don't move too much, the wire doesn't run in between clothing (from the tie down and underneath the table).

I got ambushed. I was told to record a brief message of a performer. Well it turned out to be just prior to the performance. I was given a few minutes do it during rehearsals. I could tell something wasn't quite right but under the time constraints I couldn't figure it out. He ended up mixing in singing with a piano playing in the background and making dramatic operatic gestures. All of which threw me for a loop. The audio isn't terrible and will be adequate for their purposes but I was like I got figure this out so it doesn't happen again.

I was surpised how much Lav handling noise I picked up recently. I had a pinmic on t t-shirt, hidden under a sweater. When the talent moved their arms the sweater moved against the mic, causing a loud rusting sound. I'm thinking about putting the fuzzy over it when mounted under the person's clothes.

The one thing I really like about the pinmic is the way you don't have to deal with the time/mess of taping it to hide it, so beyond perhaps adding a loop I'm hesitant to go for lots of taping down, and that may not be needed if it's just the clothes contact.

Don't forget to make a "broadcast loop" strain relief loop in the cable to absorb cable vibrations when you clip on the mic.

As shown here:
http://www.dvinfo.net/forum/all-things-audio/493008-how-use-tie-microphone-lav.html#post1627202