I'm not so sure there's a universal 'best before' date that applies, each WG is going to be different. Some will continue to enjoy the job, some will get jaded with it and end up just going through the motions. The main thing for me is that they're honest (ish) with their pictures and advertised age.
Kelly Powers in Chippenham is the longest serving girl I've personally seen. Had a mostly good meet with her, but others have reported a less positive experience. She's also guilty of not being honest about her age. She claimed to be in her late 40s when I saw her a few years ago, now she's only 35 on AW. Conversations here place her at actually being well into her 50s and most of her pictures are over a decade old. She's been on AW since 2007 but some here claim to have seen her back in the 90s, when she was trying to make it as a glamour model. She's obviously one who has become jaded with the job over the years, potentially because the 'glamourous' aspect of the career she was trying to forge didn't happen.
On the other hand, I've also seen Kitty Collins in Bristol. She's been active on AW for well over 10 years, no idea when she actually started in the job. Unlike Kelly, she's probably honest with her age and her pictures are kept up to date fairly regularly. She also still gives a good service at a reasonable price and still seems to genuinely enjoy the job.
