Yes it also include corals as they may bring some parasites with them and the rock they are mounted on can bring undesirable hitchikers.
It is not always easy to id the health of a coral. Look for no physical damage, smashed or cracked skeleton, damaged polyps (LPS). Look that the color is not pale or whitened, white spots may indicate parasites and white bands or at the base or tips may indicate RTN or bleaching. use a magnifying glass under strong lighting to look for red bugs, flatworms and nudibranches. Inspect the plug or base rock for nuisance algae, undesirable polyps or incrustations as well as potantial undesirable crustaceans.
Brownish gelatinous mass may indicate also a viral infection.
Keep them in quarentine for about 4 to 5 weeks in case they also carry parasite eggs like ich tomonts or nudi eggs.
I usually do not dip the coral imediately until it has had a chance to aclimate properly.
Typical treatments include an iodine dip or tratment with Interceptor for Acroporas. I do not favor fresh water dips.
Once in the Q tank use a turkey baster a couple of times to blow away any coating slime that could have formed in transit.
Hope this info helps.