You shouldn't advertise your business on other people's posts online.
Louis notices an online post about repairing a computer cooling fan and thinks about how he could help people with that operation.
Louis wants to help people repair their computer fans.
Louis offers the readers of the post individual assistance, through private message, if they have trouble following the instructions.
Louis responds to the post by offering to do the work, for the any reader, for a fee and the costs associated with shipping the computer.
Several readers ask for assistance and Louis is able to help everyone who needs it without violating the social expectation of the people in the network.
The readers, and the author of the original post, complain that Louis is spamming the thread and his post should be taken down.