Palo Verde is a true Dive Bar Gem, its one of those places that you have to experience to really have lived here in Tempe. Drinks are cheap, I once got a double of Glenfidich for $4.50. Its easy to bring a group and take over, the bartender will usually wrangle the more vocal regulars (as long as your group is spending cash)
BTW bring CASH! There is no credit here!
If you can make it from 2am until 6am you can begin your morning here, as far as I remember (and the memories of that night are hazy at best) with a happy hour attended by the third shift from the milk plant down the block.
This is not a bar to bring a date to, a partner that you have been with a while...awesome! If you bring a first date and she has a good time, it'll probably be with someone else.