There are lots of domains that expire daily, for varied reasons. One advantage may be that if you're buying an expired domain that was dealing in a similar business, then there is a reduction of the SEO process since the website will have been crawled many times. The main challenge I normally find is in separating the good and bad ones.
Getting a new domain name is often the preferred choice but it is always good to look at the expired domains that may come with a high page rank value. In such a case, there will be less work to do with website promotion.