In modern usage, “fulsome” has two inconsistent meanings. To some people it means “offensive, overdone,” so “fulsome praise” to them would be disgustingly exaggerated praise.
To other people it means “abundant,” and for them “fulsome praise” is glowingly warm praise.
The first group tends to look down on the second group, and the second group tends to be baffled by the first. Best to just avoid the word altogether.