The latest black hat seo tricks springing up are related to gaining customer reviews on your Google places site or other sites that are considered trusted review sites.  There are now companies that are selling customer reviews. These are done by real people who have real Google accounts and give real reviews.
It is common knowledge that customer reviews helps your local listing and can appear on search engine listings when people are searching for you. Many businesses struggle with trying to get their happy customers to log into Google and write a review, or even more difficult -- create a Google account first.
The temptation is to cheat. Cheating is any review on your site that is not a real customer who is making an honest review without getting paid. Some businesses try to get their friends to make reviews or worse yet try to give reviews under bogus accounts.   The latest fade is paying a “customer review” company to give you reviews.
Do NOT cheat, it is not worth it. It is really not that difficult to figure out what is legitimate and what is not. Google penalizes cheaters significantly and may even totally ban your local page from showing. Gaining on-going customer reviews is something you should work on and with some creativity and perseverance, it should pay off.  
Here are some review patterns that would be easy to detect and could raise a spam flag.
  •  Someone logs in from a Miami Florida IP address and gives a raving review about a restaurant they just ate at… in Minneapolis. Is it really possible for someone to be in Florida 15 minutes after they ate in Minneapolis?
     
  •  Your Google places get 25 reviews within a week but no reviews before or after.   Getting a sudden cluster of reviews when the site normally receives very few reviews will raise a flag.
     
  • Someone gives multiple reviews in the same day on several businesses in different parts of the country. The logical questions would be: how could this person be at so many different places in the country on the same day?
     
  •  Someone gives several reviews in the same day on different automotive repair shops. How many automotive repairs shops can you get your car into on the same day?
The above are just a few examples of phony review patterns that Google can easily detect.