adverb[usually as submodifier]
Deceptively belongs to a very small set of words whose meaning is genuinely ambiguous. It can be used in similar contexts to mean both one thing and also its complete opposite. A deceptively smooth surface is one which appears smooth but in fact is not smooth at all, while a deceptively spacious room is one that does not look spacious but is in fact more spacious than it appears. But what is a deceptively steep gradient? Or a person who is described as deceptively strong? To avoid confusion, it is probably best to reword and not to use deceptively in such contexts at all.