Has anyone here used spot welders with good results on autobody panels?

Not on auto body panels but I've got experience with spot welders and dishwasher sheet metal and brackets

I have a 230v Spot welder.
I don't use it as often as I would like too as I need a Larger set of Tongs for it.
I would like a Bigger set and a small set The ones I have for it now are about a foot long But they don't fit around structure very well, I end up using other welding processes Mig, Tig or Gas.

https://www.mscdirect.com/product/details/62338264

I've been practicing with it. Getting the metal clean. Yet still on thicker guage metal I'm not getting good welds when I destructive test.

Just like any of the processes the metal has to be clean clean clean! Sand clean and Try a wipe of Acetone before joining pieces. Don't use any weld through primers either.

Other than that the Time on trigger is critical too long you burn through not long enough you don't get a good weld. I do a Thousand count, one thousand one one thousand two let go of trigger, depending on thickness of material increase or decrease time.
Also clamping force is also critical its adjustable you want a good tight clamp.
The machines that we are Talking about are very simple Spot welders with no trimmers or Current control and clamping force is manually controlled adjustment.

There are Spot weld machines that have adjustable Timers built into them with other controls for current and clamping power These machines are very expensive.
You may already know all this ?

Another thing to consider welding American Steel and Import steels there is a BIG difference! I consider all import steel Junk and not weldable! it has to many impurity's in it.
Many after market if not all Import replacement panels are made with this inferior metal.
Many of today's cars are also made with this metal.
People need to demand American Steel! Don't believe me Try welding on Cars built in the 40s, 50s through the 80s then try welding on cars built in the 2000s up till today. I have! The metal is JUNK!
In many cases with the newer metals your better off using today's Metal adhesives OR using Silicon Bronze to braze the metal together.

MFG'S today build cars with MIG, Spot welding and Adhesives and Silicon Bronze welding just depends on Joint they trying to do and the metals used in the panels and location on the car.