💸 What’s the Most Expensive Mistake You’ve Ever Made?

John Talman

Good Contractor Co-Host, Sr Content Mgr
Staff member
May 8, 2025
53
68
Let’s be real — everybody has a “that one time” story.

Underbid a job? Trusted the wrong client or person?

What’s the most expensive (or painful) mistake you’ve ever made — and what did you learn from it?

Could’ve cost you time, money, sanity… or all three. We’re here to learn from each other (and maybe laugh a little too, we hope! ;)).

Drop yours 👇
 
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One of the best ones I heard that actually was NOT a mistake but rather preventing a mistake ...

Desmond Tse, better known as "The Siding Guy" who would set aside money for new folks working for him in the first year so that they didn't run into tax problems at the end of that first year. I just thought that was above and beyond and so neat of Desmond to do for those just getting going.
 
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One of the best ones I heard that actually was NOT a mistake but rather preventing a mistake ...

Desmond Tse, better known as "The Siding Guy" who would set aside money for new folks working for him in the first year so that they didn't run into tax problems at the end of that first year. I just thought that was above and beyond and so neat of Desmond to do for those just getting going.
(y)
 
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I once bid a job for one HVAC system. The homeowner thought they were getting three.
Four months later, as the project was wrapping up, they asked why two old systems and all the ductwork were still in place.

That’s when I realized my biggest oversight: I never verified the homeowner truly understood what they had approved.

The result?
  • A 4-month job turned into 9.
  • Nearly $150,000 in potential work lost while I was tied up.

Lesson learned:
Always walk customers through the estimate line-by-line.
Get written confirmation they understand what’s included (and what’s not).
Never assume “approved” means “understood.”


Small conversations up front can save massive headaches later.
 
Upvote 0
I once bid a job for one HVAC system. The homeowner thought they were getting three.
Four months later, as the project was wrapping up, they asked why two old systems and all the ductwork were still in place.

That’s when I realized my biggest oversight: I never verified the homeowner truly understood what they had approved.

The result?
  • A 4-month job turned into 9.
  • Nearly $150,000 in potential work lost while I was tied up.

Lesson learned:
Always walk customers through the estimate line-by-line.
Get written confirmation they understand what’s included (and what’s not).
Never assume “approved” means “understood.”


Small conversations up front can save massive headaches later.
Woah
 
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Not hiring a fractional CFO sooner. Not growing my skillset as a leader. Not learning how actually communicate through a sale properly. I could go on. Hahah

If you had to pick one of those to tell someone starting out and couldn't list any of the others, which would you say is the most important to do right when you're coming out of the gate to avoid the most pain down the road?
 
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Not hiring a fractional CFO sooner. Not growing my skillset as a leader. Not learning how actually communicate through a sale properly.
If you had to pick one of those to tell someone starting out and couldn't list any of the others, which would you say is the most important to do right when you're coming out of the gate to avoid the most pain down the road?
this is an impossible thing to answer but it would have to be the financials first
 
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