The flaw with most runescape scams are that they can get your account banned. But not with this coal scam.
In order to run this scam, it helps to be a high level player. Go to the falador bank near the mining guild. Say you are hiring workers starting at 500 gp per coal. Get one or two workers at first so you dont confuse yourself. Tell your workers that you will only pay them only if they have 2000 coal or more. Your workers start mining and you go do something unsefull for a while. Than you say to one of your workers in private chat that you would like to borrow some coal. Say that if they lend it to you right now, you will count the coal as double. Also say that you cannot pay them yet because you need the coal first to make some money. In most cases, the worker will believe you. If not, be polite and use your charm. Offer a better offer such as counting each coal as three so that they are closer to 2k. Eventually they will give in.
If you want to make even more coal, you can do this again. Most likely, the more you borrow from the worker, the more they have to trust you so the more coal you will get. Atlast when you think it wont work anymore, block the worker and start fresh on a new worker.
If you have 5 workers working for you at once, you will get 5k coal in notime. This scam also works on other resorces such as yews and lobsters.
