It depends on the bike. From what I read about, at least for the Vitus and Alan frames, the damage from electrolysis is seen as black corrosion "tendrils" (on the bare polished aluminum lugs) coming from the lug/tube seams. I've actually seen this corrosion on a few abused CF bonded framed bikes through the years, looks kinda nasty and scary at the same time. Not sure how it will show up on Look KG type frames as I think the whole bike is painted(?) If it is, you might see it as bubbling or raising of the paint at those seams, but I would rather see what's under the paint if possible, to make a true assesment on whether any corrosion has occurred.
Maybe you should just take it to good bike shop that that have experience and sells Look bikes and frames and they can inspect it, .......although I'm always suspicious that a salesman would try to convince you it's toast and sell you a new Look frame instead.

Good luck and tell us how it goes with the "basement" CF bike!

Chombi