Thorin and the Dwarves once coal diggers?

[Haramu]

The Hobbit

"...Just let any one say I chose the wrong man or the wrong house, and you can stop at thirteen and have all the bad you like, or go back to digging coal."

Did Dwarves after the fall of Erebor resort to digging coal and doing other dirty unwanted jobs like shoveling dung etc? I suppose they would take any job because they had lost everything and had no place to call home. Where were they digging coal? Did they work with other dwarves? Where were these exiled Dwarves digging coal? Was the payment decent or not?

And is thirteen really a unlucky number?