There are lots of benefits of using a higher temperature of water for cleaning. List them!
Effects that help in "cleaning" (i.e. : bring substances into water based solutions):
You can think of everything mechanically:
- Certain chemicals improve solubility of hydrophobic compounds (See wiki/soap)
- Time (it takes time to reach an equilibrium state)
- Temperature (Higher temperature is better - this is your question. Stay whith me)
- Mechanical agitation (scrubbing helps to loosen "junks" and break up big junks into smaller pieces).
What is Temperature?
Temperature is the movement of the individual pieces of a substance: In hot water, the water molecules move stronger (e.g. they translate faster from one point to antoher. They bump into each other harder). Think of the 4th point above: It's like microscopic mechanical agitation.
This was one point to your question.
Another point (much less important) is:
If a given amount of water is extremely hot such that it is boiling, or if a give amount of water has a high temperature gradient, then convection will happen: I.e. bunches of water will move in bulk. This could under certain circumstances improve "cleaning" because "fresh" water (i.e. water with lower concentration of the substance that is considered "dirty") is brought in.
Hot water's surface tension is lower than that of cold water. This allows it to penetrate deeper into cracks and crevices and more easily solubilize poorly-wetting substances like oily dirt, etc.