Got it, but if used properly they’ll work well, especially if the man in question wears a condom.
Saline injections, if used properly, work well especially in chemical abortions.
Does that make it right?
College kids who will conscientiously double up on contraception each and every time for their hygienic copulations (her on her endocrine disruptors, him with his latex baggies) are extremely rare. I would reckon -— this is just my guesstimate — that the fuddying and duddying involved in such fastidious contraception would make it rarer than chastity.