I currently paint for an apartment complex in my city. They have a 30 day pay out. I did earn about 16k from them last year, and it seems that I did about 10 apartments or so a month. It is a 200 unit complex. It is lower end work, but you do not generally have someone watching over you, and if you can get keys, you can come and go as you like. As Timhag says, you definitely need other projects going on. I gave a bid to paint hall ways, but am still waiting for the go. Some complexes have longer waits for pay, be sure to ask up front how long you will have to wait to be paid, as they have control in that regard. :whistling2:
I have never been screwed, but my advice is to keep good records, and if they have some kind of confirmation number to be sure to mention it in your invoice. There is always the possibility that they can loose your invoices. Especially if they undergo management changes.
Low end work, but sometimes you might just be happy to be working.
Happy painting, Paul.