As a rule, anything with more than one hyphen looks spammy. Try and avoid it - as it barely gives you the EMD benefit.
Speaking of which, the EMD benefit has been toned down for some countries. Not completely, it's not dead or any bullshit like that, and for some countries since the EMD update I swear I've seen EMD's have a bigger impact (Australia, I'm looking at you). But, mainly for the US and UK, the power of an EMD has been scaled down a bit.
Personally, I've not relied on EMD's to rank for about 2 years now. Unless I can hold of an exceptional EMD for a reasonable price - and by that I mean 1 or 2 word exact matches with no hyphens - I'd much prefer to rank for a brand rather than an overly long or spammy domain.
To directly answer your question: board-certified-plastic-surgeons.com - avoid that like the plague. boardcertifiedplasticsurgeons.com - eugh, I['m sure you can do better then that.