Seeing as it is the owners of the property that tied on the threads I would assume that it is some form of good luck charm. Hardly likely that they would be putting out something "evil" or nasty on their own property, especially a property ostensibly earning them money. She might want to ask them, as an expression of interest in their culture.

 

I don't think it's a "bad" or "negative" thing. I found this:

It is also a part of Indian custom to tie a long red string around the wrist of loved ones during prayer as a mark of protection and to safeguard against the evil eye. Individuals wear it for a month till the thread wears off.


which would suggest that the red thread was tied on the doorknob as a mark of protection. Red threads can also symbolize blessings upon the person wearing them around their wrist.

The color blue is related to Lord Krishna, one of the most important Hindu gods.

Yellow symbolizes business/merchant and wealth.

 

I was thinking the same as Ravenlost about the threads. I was familiar with the red one warding off evil, but did not know about the other colors. Very interesing. I have seen in documentaries of India, they tie colored fabric to trees for prayer I belive.

 

Sounds like they're blessing their business.

 

Thanks folks, I will pass this along to her. Another friend of ours suggested that it is a way to see if the buisness is being cleaned properly, but if all three are tied, on each doorknob, I wouldn't think that is it. In any case, I agree, communication would be a very good step in this.
God bless you and yours
Deb