Combination of multiple spilling of beverages maybe some food too. Either way it appears no one ever tried to clean it up. If this was an older rug I would just replace. I'm a true Bissell fan
Answer: We are happy to hear that you love BISSELL! For general food stains, I recommend that you blot up excess liquid with a clean, absorbent cloth. Generously and evenly spray the area with BISSELL oxygen based product such as OxyPro®. Gently work the solution into area with a small brush, sponge or cloth using light strokes from the edges of the stain to the center. When you reach the center of the stain, lightly pinch an upward motion. Do not rub the stain. Wait 5 minutes. Then, use your BISSELL upright or portable deep cleaner over the affected area.
If this does not work, and your stain turns out to be tougher than expected, I recommend trying BISSELL Tough Stain Pre-treat for Carpet & Upholstery. As always, follow up your pre-treated carpet with a good deep cleaning from an upright or portable machine!