...well to be fair I have seen complete garbage be pretty strong
but what I recommend is getting a sledge hammer, making a weld on something you actually want to weld with sacrificial metal with all the same lever lengths of torque and giving it a test till you are winded...
Same deal here, but please allow me to share my humble story about weld integrity going south...
I've had the A frame of a professionally made box trailer snap at the body weld join, going over a slight road hump whilst going downhill in the main city at peak hour, quite the adventure!
A scene Hollywood could use in the next Avengers or Justice League installment
Safety chains won't bail you out of that worst case towing scenario, because they are joined to the A frame and tow vehicle, with the fully loaded runaway box about to partake in free flight...
Luckily the bottom welds
(TOTAL RECALL CORRECTION: the bottom of the unwelded square tube) just barely held enough for me to drag the fully loaded trailer (upturned 75 degrees and scraping ground!) slowly down the hill to level ground and into a side street,
where I managed to level it up by jumping on the top front whilst jacking up the rear, empty the contents and jerry rig secure with rope,
well enough to get the sucker to a local trailer fabricator who pointed out the obvious weld error that should not have been done that way
He re-welded it at the snapped join for aesthetics and welded on a matching extra tube bar under the A frame to the mid section of the box,
in a way that offered maximum support and no weld area to flex or snap,
and it looked cool and original once spray painted over, with that 'never happened' vibe
Needless to say, any trailer or tow rig I get in the future, no matter how well built, will be getting that mod done to it,
and chains strung inside the tubing from mid box to mid A frame,
just in case too many zombies hop on top during the next Z apocalypse i.e. if a trailer snaps at the A frame it's SOL City, someone will be hurt, dead, bankrupt,
most likely all three !
That was a lucky day for me when I think back about how it could have been a lot worse, had I been driving uphill or going 100kph on a busy freeway.
fwiw: the trailer load was balanced perfectly with a slight bias toward the tow vehicle, but how can you forecast a disaster like that?
on top of that the weakened weld points had a nice even coat of paint so even a concerned owner's regular inspection is a waste of time and investment in false security
So yeah, whether it's a good looking bead with obvious penetration burns, or stringed along bird droppings that have 'held solid for years',
all structural welds should be checked and rechecked for flaws and wear and tear stress.
Same deal with soldering, I've sorted out a lot of 'good looking' and 'shiny' joints that were actually dry, cracked, or just sitting pretty on an oily track and or component leg, on cheap and expensive gear
to know better and always assume nothing.