It is inappropriate to give someone such a toy in most cases because it encourages participation in sin. Pleasuring oneself with toys is a sin of the flesh. A husband and wife may respectfully gift each other with such toys if they plan to use them on each other to enhance their procreative marital relations in some way--maybe.
Many people have more liberated views of sex now than in the past. There is no need to feel shame about enjoying sex that does not conform to traditional behaviors. Men and women appreciate sex toys. When a person knows the recipient well enough to know they would not be offended, a sex toy is an appropriate gift.
It depends entirely on the context and who the person is. If you're walking up to an elderly religious lady at the park and giving her a sex toy when you don't know her, that's probably inappropriate. If you're buying it as a gift for a friend or spouse then it's not inappropriate at all. A lot of people would find it funny or be appreciative, others would be outright offended and disgusted. It depends entirely on the context of the situation, there is no solid clear black and white line here.
Giving a sex toy to the right person is not inapropriate. For a spouse, significant other, or a close friend this can be a great gift. It would not be appropriate to give a sex toy to a random person or your boss, unless you are a sex educator or in the sex toy business.