They often expect you to commit to working a certain number of hours per week, which is generally part-time. They will pay you an hourly salary for that work, so it is really more of an at home job situation than it is in an entrepreneurial way to make money online. Still, if you want to get involved in political activity, and you have the time and motivation, this could be a way to monetize that passion.
One factor that you must be aware of though is that Care.com is a peer-to-peer arrangement. That means that you will be in direct competition with other pet sitters in your area. You must price your services competitively in order to get business. Once you begin to develop a list of regular clients, you will be in a better position to raise your rates. This will be particularly true as you get referrals from those customers.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.