My house has blown-in insulation (cellulose, I think) which I understand was done about 30 years ago. House is probably 70 years old. Obviously the insulation has settled, as the snow melts off roof in no time at all! House is a Cape Cod, about 2500 square feet.
Just as bad, or worse, is that this is the filthiest house I've ever lived in! I can't keep it clean. There is this (kind of greasy?) gray dust that clings together in clumps and accumulates so fast I can't keep up with it. I live here alone, and don't track in this amount of dirt. Even a large family would not track in this amount of dirt! I don't even open windows often, so it isn't dust blowing in, and I live NOWHERE near anything putting out dirt from smokestacks of anything like that. I finally tumbled to the fact that it must be the insulation leaking out and being blown around by the furnace and A/C.

COULD THIS BE RIGHT? If so, is there any feasible (as well as economical, since I'm a senior on an extremely small budget) way to remedy this? It's making me crazy to live here because I can't keep the place clean. And, believe me, it's not just that I'm an obsessive cleaner - this is a dirty house. If NO ONE lived here, it would still be a dirty house. THANKS!!!


 I would tend to agree with your assessment of the cause 100%.  Most likely, in the process of installing the insulation it was inadvertently blown into a cold air or heat run.  In some cases in older homes such as yours there is an open cold air return into the attic.  If this is the case it is also the source of the insulation being pulled into your system.  
I would recommend that you contact an experienced insulation contractor and ask them what they would charge to do an inspection to try and locate the source.  Another option would be to have all your heat runs and cold air returns vacuumed by a professional company.  This might be costly but you could get an estimate in advance. 
You can inspect your heat runs and cold air returns yourself by shining a flashlight into them.  You may find one or more with an excessive amount of dust or insulation showing.  If so, you may attempt to vacuum it out with a shop vacuum.  If you get more than one tankful, I would recommend you stop because you are just pulling it through the system from wherever the source is located. 
A short-run solution would be to change the air filters on your furnace system once a month and replace the air filter with an inexpensive (approximately $3.95) 30-day filter.  This would most likely temporarily help the situation.  
I would recommend that you deal with this sooner than later because you are breathing insulation that has not been designed to be ingested and, therefore, could cause you a health problem.  Also, if this problem isn't dealt with it could shorten the life span of the furnace system. 
I hope this information helps you to deal with your unusual situation.
Bruce Jones
The Insulation Doctor