If you are a liar, then don't expect people to know you as anything but that. Is hard to need a job and not get it. I get that, and it is nice to get some help from the people that love you so you can get back on your feet. But that kind of favor isn't normally something that you ask for. You can, but it will be just that: a question. Then it's on the other person to decide whether they want to help you out or not.
In this case, the sister was willing to help her unemployed sister prepare her résumé and her interview, but not vouch for them at her job so they would give her the interview. This struggling sister did not pay attention to what her sister said and did whatever she wanted to. Now she has to deal with the consequences of her actions.