Talk to owners of other condos in the building. If you buy, they will be your voting neighbors who you will see at least once a year to vote on spending money on various solutions to common problems. You may as well get to know some of them right now.
Some of them will have had no problem with mold; a lot depends on how much living they did there. Daytime Presence causes humidity buildup.
The news is not good. Since you can see mold, there is going to be even more inside the walls.
edit: you can start with a quick review of the yearly meeting's minutes, to see who is who and what concerns were addressed formally. This is a good step for any buyer to do. It tells you things that the individual sellor may not disclose easily. This is one advantage that condo living provides to buyers.