I spent a few years on here looking at the builds before attempting my own.
When I discovered the forum, I thought I'd knock out a cabinet the following weekend.
I could have, and it would have taken a fraction of the time and cost and been 80% as good.
But while browsing the forum for ideas I realized how high the bar was here and I decided to wait until I had learned enough to build a more polished and interesting cab. I bought an X-arcade tankstick and used that for a few years while I learned the ropes.
On my current cab, the only major mistake was cutting the hole for the D button in the correct spot, thinking it was wrong, then filling it in and redrilling it in the wrong spot.
It's still like this.
As far as what is half assed on my cab, my joysticks are attached to the CP using half inch screws straight into the mdf rather than doing them properly. Originally it was only the 2 mounting points of the Sanwa JLF S plate, but that got loose. So I drilled 4 more holes in each plate so 6 screws are holding each now. I wouldn't trust it for public use.
There are a few spots where the slot for the t-molding was wider than it should have been for whatever reason and I hot glued the t-molding in place, but I don't think that's all that uncommon.
I didn't make any noob mistakes because I read the threads on this board for a few years before building it.
Link to the cab is in my sig.