Checking for damp carpets helps. Mine had damp carpets when I bought it. I was hoping the weather strips were tired but it turned out to be a bloody hole in the scuttle panel right under the windscreen. If it has a sun roof, check round the sunroof aswell. Good chance of bubbling round there. I also think it's worth checking as much of the loom as you can see. The list is endless really lol. It'd be naive to think that unless you're paying around 5K you won't have work to do. Worth it though.