epson wf-2860 keeps getting ink on the back of my prints, smudging everything. what's causing this?

Ink has likely built up on the paper guide rollers inside the printer. You need to run the Paper Guide Cleaning function.

1. First, load some plain Letter (8.5x11 inch) or A4 paper.
2. Press the Home button on your printer.
3. Select Maintenance.
4. Scroll down and select Paper Guide Cleaning.
5. Follow the on-screen instructions. The printer will feed paper through to clean the guides.
6. Repeat the steps if necessary until the paper comes out clean.

If that didn't work: The print head path inside the printer might be smeared with ink. This requires a manual cleaning with a water and mild detergent mixture, cotton swabs, and a flashlight. It's a more involved process—if the paper guide cleaning didn't solve it, you may need to look up the specific steps for cleaning the print head path.