Funny noises from the suspension - IIRC these have a fairly sophisticated suspension setup, which might mean worn bushes and all that.
Just dug up a German buyers guide for those - if it's got a sunroof, very carefully check the C-pillar and the rear shock mounts as they can rust badly if the sunroof drain is blocked. They also recommend checking the trunk very carefully for rust, plus the rear wheel arches, rocker panels and if you can, remove the rear seat (which should be very easy supposedly) and lift the plastic/rubber covers over the wheel wells/tubs as they're another typical rust spot.
On the front, check A-pillars, the strengthening plates for the front shock towers, and the two 'frame' elements that hold the motor.
Blue smoke can be valve guide seals, but on high mileage ones it can be engine wear, too. Also, cylinder head can suffer from damage if the engine isn't warmed up properly.
If it's got a slushbox, the BW65 box in the early ones needs more servicing than the later ones and they hint at a parts availability issue. Manual boxes are supposed to be pretty robust.
Well, that's at least some rough paraphrasing of what they said
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Sanity is vastly overrated.