That's incredibly hard to say. It would depend on the type of person your sister is, what the cost of living is (70,000 in NYC is living month to month and usually ending up in the red).
I would say if he's a frequent user, it would be hard to miss. She would at least think he's gone crazy, unless he was using it all along. Crack addicts are some of the most vicious, dangerous, crazed of the addicts.
Personally, I never understood the obsession. I've watched crack addicts do a hit and then lock and bolt the doors and sit for an hour obsessively arranging pencils in a row. Try to stop them, they get violent.
I remember a woman I met telling me she used to get obsessed after using crack and have to sit with her back to the door because of the paranoia. She told a "funny" story about how she slept with a guy to get some crack, and after doing some, spent the whole time they were having sex trying to shove her foot up against the door so "no one could get in".
Great image, guy on top of her, crack pipe to mouth, and trying to edge towards the door and desperately waving her foot at it.
It just doesn't sound like an enjoyable experience to me.
I would have to believe that your sister not only knows what is going on with her husband, but is doing it herself as well. I find it a little hard to believe that a combined income of $70,000.00 per year doesn't at least keep the lights and water on. But, they could have more debt that nobody knows about, personal loans, etc.?? How about daycare costs, that's mighty expensive! Many people, especially this year, are having problems making house payments.
Now, I assume you have asked if she is on drugs because you said she claims she has never experimented with them. Do you honestly believe her? I have an uncle who has been on crack for years - you can tell just by looking at him. Some people hide it better than others though. If you, your sister, and your family are all in the same area is it possible to drop by without calling first? When my husband and I were doing cocaine, we'd hole ourselves up all weekend, not answer the door, phone, etc. It would have been obvious to all who stopped by that we were hiding for a reason!
Have you sat down with your sister - just the two of you and discussed this without her husband around?
Its hard to say whether or not your sister is using. If she is not telling you the truth, you cant help her anyway. If you press her and call her a lier, shes probably never gonna tell you her problems. Shes only gonna feel that you are trying to bust her in something. Shes not gonna feel that you have her best interest in mind if you treat her in a way she feels your trying to bust her in lies or drug use. As far as being financailly screwed up. If shes not using imaging how stressful it is for her to be living like she is. If you assume the best of her and she sees that maybe she'll start to open up to you about her life. Your not going to offend her into a relationship where she feels safe enough to open up to you. You can love her into one though. She has alot more problems than crack use if she has an addicted husband and financial destruction. She has got to be under major stress. Try loving her and being kind to her, maybe then she'll start to open up to you.
I'm sorry but it doesn't look like you have enough info to be sure, or at least not enough info for me to be sure. Crack is a HARD drug to quit, and if he admitted it, and he is still acting the same way, and having the same problems, then he probly is still hooked. 70,000 and no electricity? Big problem, I'm not sure what but big problem. Maybe you could start hanging out w/ your sister more.