Buying expired domains for seo

Definitely Yes, but you have to know the following questions answer before buying any expired domains.  

1. How do I evaluate an expired domain name? What price should I pay?
2. How do I know whether an expired domain is a scam?
3. How do I know that the links to the expired domain are not going to drop after I purchase the domain?
4. What metrics should I be looking at to gauge the quality of the link profile?
5. How do I know if I’m looking at a relevant expired domain?

Can be, but risky

1. If you're asking this question, I wouldn't say you're knowledgable enough to successfully pull it off without being detected.
2. If you do decide to go ahead and do it anyway, be careful - the best SEOs even get caught at this game, so always prepare for the worst, and avoid if you're looking for longevity.