The slates are NOT pinned on an Olhausen table. If it was a black laminate table, chances are it is either a Champ Pro, or a Grand Champion. Both are very good tables in my opinion. The Champ Pro has big wide legs and was used in many tournaments back around that time. Very masculine looking table:
The Grand Champion is similar, but had narrower legs and adjustable leg levellers. Here is one with the oak finish:
Both, can be very good playing tables if installed properly, but that goes for pretty much any table. The only real cmomplaint people have on these is the "Olhausen rattle". The rubber and facings on these tables are a little soft compared to other brands. That combined with their pocket geometry causes the tables to reject a lot of balls, especially if they are shot hard. This can be corrected by a knowledgeable mechanic using the right materials.
As far as the bondo problem, that could have been an isolated incident. If the slate screw holes were filled with bondo, it can be chiseled out with a flat head screwdriver without too much effort. Of course if the installer was any good, they would have covered the screw heads with a small piece of tape or paper to prevent bondo filling in the head of the screw. That would at least save replacing hardware. It's also possible they used wax in the holes, in which case you can just push a Phillips bit through the wax and remove the screw with a powered screwdriver.
If that is the table you're looking at, both are good playing, good quality tables in my opinion. Of course the playability of the table is only as good as the quality of the mechanic, so definitely keep that in mind when it comes time to get it installed.
Hope that info helps!