This is one of my favorite questions and I constantly need to keep doing this because I am unable to decipher or tell when certain things are not clean. When it comes to dishes, glasses, and pots and pans, I can usually tell if things are clean by running my fingers along surfaces. If I feel bumps and sticky stuff, then I know that it is not clean but when it comes to stains it's a different story.
In the kitchen, stains are my main challenge because it is difficult to tell if a stain is there unless it is sticky or bumpy. When it comes to clothes, the same thing applies. When it comes to carpets and floors and furniture, it's all the same. So, if mom is around I can ask her but if she is not then I have to be super careful. Walls and doors are also something for me to be careful with. My fingers can usually tell if surfaces are dirty but in many cases it is impossible to feel spots and stains.
I'd like to see the development of some sort of device to tell blind persons when stains and spots are present. In the meantime, you can learn more about how blind persons deal with such things as spots and stains by reading the "Household hints" or "Housekeeping" catagories of Fred's Head.
I'm Donna J. Jodhan your friendly accessibility advocate wishing you a terrific day. If you'd like to learn more about me, then you can visit some of my blog spots at:
Donna Jodhan! Advocating accessibility for all: http://www.donnajodhan.blogspot.com
Weekly Saturday postings on issues of accessibility: http://www.sterlingcreations.ca/blog/blog.html
blogs on various issues and answers to consumers concerns: http://www.sterlingcreations.com/businessdesk.htm