So here is my 2 cents for people butting in when not asked.
Acknowedge and ingore.
"Oh really!!, thanks for the advice."
And the complete blow off that there is no reponse for.
"Thank you, for caring enuff to share that with me."
Both of these work well. I tend to not ask for advice unless I need help with something and tend to not give it unless asked. Now I do take everything that is said with a grain of salt
cause alot of people concider themselves to be the utmost athority on everything. And you have to take in to account that alot of people talk to hear themselves talk. Also there are many people walking around with nothing better to do than butt in ( the reason these man are out walking round is cause their wives are sick of listening to them ramble bout this and that).
On the other hand Sean, the paying customer is not always right, but they are still paying. I am not saying that you are wrong in treating the paying customer as the correct one.