yes you should see the factory spot welds in the trunk gutter and very other location as well.
If not it is a good sign the car has a repaint, but then again one would not apply paint down into the gutter.
Or your car has had full quarter panels installed already and since the most common method of welding in the collision field is MIG you wont see spot welds. Look up underneath at the gutter from inside the trunk, can you see any burnt paint? Most shops do not address the backside of panel that they just welded on and you normally see burnt paint, bare metal and sometimes small pieces of MIG wiring poking out or half welded screw holes.
Replaced panels are pretty easy to spot, just look at the places you nomrally dont see like door jam area, backside of panels stuff like that.