A good relationship with loyal customers is worth a fortune. That's the most valuable thing any business can have. The key here is to build your large list of lifetime customers who trust you. Achieve this and you're set for life.
During the earlier stages of my career I was fortunate to have worked for a large corporation that had a management development program for up-and-coming managers. This program combined formal management courses with on the job training. The job training involved assignments to different divisions in the company. Two learning goals were mandated by these assignments:
How many times has bad advice gotten you into trouble? Yeah, everybody's saying and doing it, so you jump on the band wagon...and guess what...you get the same results as they get. Maybe it's a comfort to know that you're not the only one who played the part of the fool, but when it comes to marketing...you may not have enough leeway to count the loss and go on.