Yes, this can be a little confusing but also helpful when you understand what’s going on.
In Scotland a married woman can legally be known by both her maiden name and her husband’s name. In fact on gravestones it is usually a woman’s maiden name that will appear and it will say something like “wife of John Smith”. This still happens to this day.
In the census it is a little more haphazard, usually she will be listed with her married name but it is not unusual to see a maiden name. The 1841 census can therefore be confusing as there are no relationships listed but then again in most families it is quite obvious.
In our own census indexing project [http://www.maxwellancestry.com/census/default.htm
] we have indexed these women under both married and maiden name (when it is obvious) to save confusion. We have added an alternative surname column too.
So if you do come across the maiden name in the census it will make it much easier to find a marriage.
Another thing to remember is that if the woman is a widow the chances of her being listed under her maiden name increases dramatically and if you don’t know what to look for these widows can be hard to find. I usually look for her children in the hope she is living with one of them.