Never! I always:
* do my homework 1st
* always make sure I have a 30+ day trial period
* always demo the piece in my house, in my treated room, how does it sound with my other gear (synergy)
* sometimes the new gear is a newer piece of the same brand with the same sound signature that I like
I have had some new gear that made me change some existing pieces or get rid of things that I no longer needed. For example, my new speakers sound better without the 1st reflection panels installed.

