Very interesting question. My kids are 9 and 5 and for yrs I was too permissive and didn't realize it. Seriously. I know that sounds nuts, but what typically happens (according to Aletha Solter of Santa Barbara (I attended her FREE eye opening workshops)
http://www.awareparenting.com/
is that parents who were raised very authoritarian (me) tend to go the other end of the extreme spectrum (permissive) to avoid the hell of that. What parents don't realize when they do this, is they are causing a whole other set of problems with their children.
I think you should listen intently when they complain and when they ASK, then answer (like someone said below) do you really want my honest answer? Would you like some suggestions from me? (some people don't want unsolicited advice, so ask).
Of if they complain and don't ask for advice, ask them, "would you like some suggestions?"
If they answer yes, then be sure to lay it on (GOOD advice, good heartfelt guidance) not lay on all YOUR frustration with how difficult you find it to hang with them b/c of how hands off they are.
I am a very open person and I would have LOVED guidance back then. Good guidance is not the same as any excuse to dump on and criticize a person.
Some helpful links I found, this one was eye opening:
http://www.devpsy.org/teaching/parent/baumrind_styles.html
Aletha Solter had an AMAZING handout that outlines the 4 parenting styles, how the parent acts, how the kids act and what it results in each child. Pretty shocking. I can't find it online. That was eye-opening too. Maybe if you contact her she can mail you a copy of her hand out.
Barbara Coloroso's book KIDS ARE WORTH IT
describes 3 types of parents: brick wall (authoritarian), jellyfish (permissive) and backbone (authoritative) - best, most balanced parent
http://www.kidsareworthit.com/
That's a very helpful book. It breaks the issues down very nicely. ALL her books are great.
Some of your friends will get on the ball and recognize the problem and work on it.
Others won't. Others will find resources (and twist the meaning) to make excuses for their kids. I heard of a friends friend who read YOUR SPIRITED CHILD by Mary Sheedy Kurcinka
http://www.parentchildhelp.com/
(an excellent book) and just said "oh my child is just spirited". Yes and no. And Kurcinka's awesome book (helped me to understand myself, my kids, other people, other children ) is not a defense for kids who are "out of bounds".