General linking etiquette:
If you are adding your *commercial URL to a free directory, free website, free forum, free portals ect, it is normally required that you link back. Some site have a specific reciprocate link policy, some don’t, some may have one but don’t have time to enforce it. Whichever the case is, the correct thing to do is to link back. If you don’t, it just shows that you don’t understand the web etiquette, or you don’t care. Either way, you’ll end up looking clueless, arrogant, and getting your URL deleted.
If you are adding your commercial URL to a paid directory, paying members-only panty site, subscription portal ect, you are essentially advertising your business via someone else’s business, therefor you can expected to be invoiced or banned for breaching the site T&C, depending on the site advertising policies.
Always check the website linking policies before adding your URL, as you will find that most commercial websites forbid any kind of advertising via links.
Don’t be clever
If you think that watermarking your photos with your URL does not count as advertising, think again. When a commercial sites say NO ADS, it really means NO ADS in any form or shape. Even if you can’t click on it!
Permission to link
You don’t need permission to add someone else’s link to your own website, however, it is polite to ask first, and it is OK to ask someone to remove it, especially when the link is merely (ab)used for SEO purposes.
If you have any questions, please feel free to ask me!
*A commercial website is a website where a individual or a company sells a product in exchange for money, if you sell used panties on your website, your website is a commercial one.