when to draw the line?

When you go into a house or business and you see that the carpet is need death, do you guys try to revive it or walk away and advice the customer to get themselves a new carpet. If you try to revive what steps do you take.  I ran into a carpet (15+ yr old commercial glue down) that had stains every 2 to 3 feet And God only knows how long those stains have been there. I used a roto vac with brush attachments on a portable. When i finished, I had discoloration, and the carpt in about a 4X6 area began to come apart to the point that i could see the concrete behind the carpet. WHERE DID I GO WRONG? new to the biz good advice needed. 

never walked away cuz it was too filthy

cuz I know I can make it look MUCH better

LISA IS WRONG............WHEN A HORSE BREAKS A LEG.........YOU SHOOT IT..............WHEN A DISH BREAKS YOU THROW IT OUT...........DO THE SAME FOR A CARPET THATS FALLING APART, WHAT IS THERE TO SAVE.............BUT IF YOU DO ATTEMPT THE CLEANING AT THE END DON'T CHARGE YOUR CUSTOMER IF YOU HAVE ANY MORALS..........'CAUSE YOU KNEW IT WAS IMPOSSIBLE

                            NIGHTRIDER