Buying a 4 plex

[Valerie Young]

Yesterday I looked at a 4 plex (first time looking at a 4 plex ever!), which currently has all units rented out.  The property is in overall good shape.  It has a new roof which was put on a few months ago, a brick exterior.  And the windows seem to be in decent shape.  Because of occupancy I was only able to see one of the units.  I liked the unit we did see, but I'm worried about putting in an offer before I can see the rest of the units.  Is this common practice??  Should I insist on seeing all of the units before I put in an offer? 

I'm used to buying SFRs which need some fixing up, so I'm just thinking that they allowed us to see the best unit.  I would hate to buy it and have to immediately stick money in, without my knowledge of anything being wrong.  Any advice??