I personally dont sell text links because i dont have time to manage relationships with the buyers and as casinobonusguy pointed out, its just not where the money is.
If your site isn’t very large or complicated you can sell a few links and consider it an extra source of income. The text link buyer isn’t necessarily after your traffic. If your site is content rich then it isn’t worth it unless the the buyer has a strong and relevant site. If the site is relevant, on topic and stronger than you it might actually be beneficial to have the link from an SEO standpoint.
If the links are off topic or there is too many of them you might get penalized for selling links. This doesnt generally effect your s.e. rankings but scratches your link trust which will make you just a little less attractive for a meaningful partnership.
If none of that makes sense just listen to casinobonusguy and ignore the marketers 99% want something for next to nothing.