I can't speak for WeWork specifically since the closest one to me is about 3 hours away, but I'm renting space at another co-working place near me starting next week. The space is $275/mo for a dedicated desk, compared to $1300/mo for the cheapest (second floor) office space nearby. And that $1300/mo does not include furniture, utilities, or coffee. If you need an office, it's a no-brainer. And I'm not going to meet clients at my home.
I'm not sure what "noob" factor there would be... meeting clients at home would be worse. Meeting them at a cafe would be better than at home, but worse than an office. WeWork or any other coworking office is one step below your own office, but far above the alternatives. If you're worried about the signals you're sending to clients, at least a rented office (even at WeWork) sends the message "we have enough money to afford this". A cafe or home office does not send the same message.