The author of this piece says "almost never" -- I will go further and say that should be "never" for consumers.
That is, unless you are a professional auto rebuilder, stay far away from salvage title/rebuilt title cars and trucks, period.
They will be nothing but grief for you.
Why You Should Almost Never Buy a Salvage or Rebuilt Title Car
While a salvage or rebuilt title doesn’t necessarily mean the car is a death trap, the bad usually outweighs the good.
It may be tempting to buy a car with a rebuilt title because of its low price point, but what’s tricky is you don’t always know the extent of the damage that gave it a salvage title to begin with.
“It’s very hard to determine if a car is back to pre-accident condition,” says Jack Gillis, executive director of the Consumer Federation of America. “I recommend just staying away from those types of vehicles.”
Sometimes a rebuilt car can look shiny and new on the outside, but still have some serious internal problems. Flood damage is a prime example of this. Cars that have been damaged in a flood are especially dangerous to drive because it can take months or even years before the water corrodes the electric and mechanical systems. You should always ask an experienced mechanic to inspect a rebuilt car before deciding to make the purchase, but even then, it’s a risky move.
“If a vehicle was in a flood, you can’t fix it. It’s not rebuildable. If it was wrecked so badly that it was salvaged, chances are the frame or unit body was compromised,” says Shahan. “So if you’re in a subsequent collision, it’s not going to give you anywhere near the same protection that you would’ve gotten if it was an undamaged car.” . . .
Much more at link here.