It depends on serveral factors, including exactly what extension, how long the dictionary word is, and if it has a prefix, or suffix. For example, un-,-ed,-ly, and others can bring down the price significantly. I would say to most likely pass, unless it is a good .com, or a great .net, and in a few instances, an amazing .org, but other than that, you will have to find premium dictionary domains, to get any return on your investment.
Tom