Your washer has literally one job. You use it to clean your clothes. However, if you are pulling your clothes out and notice new stains that weren’t even there before, your appliance has a problem. However, there is no one cause that will make a washing machine start staining your clothes. You will need to look at the color of the stains to deduce what might be happening.
Oil or Grease Residue
If you have dark, greasy stains on your clothing, this could be caused by a machine defect. In some models, a malfunction could cause lubricating grease to access the tub. It could also be caused by previous loads as well. If you washed something with oil or grease on it, there is the chance it will linger in the tub.
If this is your cause, you will want to run an empty load on hot water settings using white vinegar in place of detergent. This will strip the oil residue out of all the nooks and crannies. It is best to wipe down the inside of the tub with a clean cloth afterward just to make sure it worked, however.
If you have reddish-orange stains on your clothes, that is most likely caused by rust. If your washer tub is manifesting rust, you will likely want to replace it as the problem is just going to get worse. A drum replacement is complex but cheaper than getting a new washer. Unfortunately, as the drum has many holes, it can be difficult and near impossible to properly patch the enamel to prevent rust from spreading.
If your clothes aren’t necessarily stained but feel very greasy or waxy, then it is caused by your fabric softener. Using too much fabric softener, or packing clothes in so tight that it can’t distribute evenly will result in waxy feeling clothing.