On a semi-unrelated note, a very short story:
Years back, I was at my friend's house when his grandpa came over. His grandpa was talking with his mom and said something about "n*gg*r boys playing in the park". Granted its an extremely racist word, and I had all right to take offense (I'm black), I wasn't offended. It's unfortunate that over his lifetime, that word is the simplest way he can describe black people. At the same time, it was completely devoid of hate or ill will. My friend's mother pulled me into the garage and apologized profusely. Personally, I'm sure that some people might have taken offense, reactions obviously vary. The amount of offense I took from it would be like if a young child spoke the word after hearing it somewhere, having no idea what it meant. The innocence of it was why I wasn't offended. I might not be offended but surely I would educate the child as to the appropriateness of its use. When and where and to whom, and how it is said...
Of course this is an instance where the use of the word makes sense in it's application. It was used as a descriptor in-line with its definition. It wasn't being construed into something outside it's standard connotation.
While I believe it to be unprofessional and frowned upon, if the intention wasn't there, I can't hold it against them. If someone made a joke about cancer, that's pretty insensitive. My father has cancer, and it's certainly no joke. Do I immediately begrudge them about it? Does it immediately bring forth painful feelings? No. I might let them know its distasteful to make that joke without knowing their audience, but if they are ignorant of the conditions than I wouldn't really take offense... I wouldn't really be hurt by it. If it was a personal attack against my family where they were being cruel in reference to that fact, then I would certainly be offended and probably hurt. The intentions were to offend and to hurt.
The older you get, the more likely that a "your mom" joke or jest poking fun will be met by someone who has lost theirs. As we get older, it becomes more prevalent. The question is whether we start to shift to "your sister" jokes, as if it was better.... or completely scrap all familial jokes and references (and all forms of social jesting where we poke at friends in a friendly way to build comradery), or simply educate ourselves as to our audience beforehand. If you know he has a sister in good health, go ahead and make that sister joke... BUT in the case you did make a joke about their mom, and they HAD in fact lost their mother, but were ignorant of that fact, in personal experience, the audience member is usually unoffended but lets you know the truth of it. Naturally, they expect you to refrain from those types of comments with them from that point. It should be stated however, that same person should take no issue when that joke is made to someone else, provided their mom is alive and well... because for them it's different.
The intention, and who its aimed at are equally important in assessing the nature of its offensiveness. Yes its easy to decide that using that word is unnecessary and arbitrary, and to cut it out of our word bank. You run a lower risk of offending someone. The word **** is a bit different however... Even if you didn't mean it in the extent of it being an incredibly terrible act of violation forced upon someone against their will, with a word like ****, to hear it used nonchalantly is equally offensive mainly because even at best, you are dumbing down the seriousness of the act; you are taking away from the person who was affected. With the word gay however, I don't see that to be the case. The term f*g or f*ggot however, are intrinsically hateful words, like the n-word but are used to describe homosexual people. It would seem rare to me that those two words would be used innocently, devoid of hateful properties, so I would generally discourage their use; just as I would generally discourage use of the n-word. Without intention however, is it wrong if the word n*gg*r was to be used in a discussion about the actual word. Let's say in a book that is talking about the historical roots of the word, etc. Of course it's not wrong when used in a non-hateful, literary sense. Similarly we need to look at intent and audience in judging the appropriateness of the use of words.