However, if they work for a reputable Agency, (not as self employed) then they will get good wages and all the other benifits that a regular employee should receive by law which includes sickness/holiday pay.
I Know, as part of my business interest's do include running an agency that is not connected to the cleaning industry. The 40-50 or so employees actually get paid more than my regular clients own employees, they enjoy all the benifits of being a full time employee and as they work for an agency their destiney is in their own hands and only work when they want to work, they only accept assignments that they want to do, they can earn as little or as much as they like. Some people prefer flexibility and with an Agency they get it.