A good standard is around 8% (roughly one month vacant/year), but in super hot neighborhoods it will be lower, and in lower-demand neighborhoods it will be considerably higher. 

Avoid hot markets.  

Some say 2%, but Arlington is a hot area and rentals will always be in demand with DC close by.If 1% of rent is too high for the area, drop your purchase price.If your purchase price can't be dropped, then it doesn't make sense as a rental investment.

In Southern California, as in any hot market, (San Fran, Vancouver) the second a multi-family building hits the market, there is a sea of offers.  

They will say that even though the market has been red hot here in CA so I know that they are not really closing any transactions.

How old are the furnaces, hot water heaters etc....This is stuff you need to figure out during your due diligence.  

I recently went under contract on a property for $400,000 (no financing) in a very hot market.

As a former accountant, I can tell you that the IRS started cracking down HARD on that issue over 20 years ago and they (plus each state) LOVE to find fields of biz that are ripe for he picking and whack them hard, over and over and the flipping/rehabbing, etc field is apparently one of the hot ones now!

When a buyer or seller is hot ... close and sign, make sure your appointments are made when all parties are present too, otherwise they turn cold and blame it on the one who wasn't there! 

marvin stewart i live in Alexandria and I use rod noles property management.