How business can avoid the pitfalls of photo-sharing services
Losing control of your photos
Some photo-sharing services, such as Flickr, don't keep all the photos uploaded by users who have a free account. Flickr also compresses photos uploaded by free account holders, so if you don't keep a high-resolution version of your photo, it's gone forever.
If you want a permanent home for original photos that you want to retrieve later, make sure to choose a service and account that will allow you to do this.
Breaking the rules
All photo-sharing services have rules about posting appropriate images and comments. Anything illegal or hateful is not permitted, and different sites have different rules regarding nudity and the like.
Copyright laws also apply. Flickr wants original photos only, while Pinterest expects you to check that you're allowed to pin something and to provide its source.
In addition, Flickr has rules about not engaging in overtly commercial activity, and Pinterest has 'Pin Etiquette' (e.g. 'try not to use Pinterest purely as a tool for self-promotion'). If you break these rules, you will at least be warned and, at worst, have your account cancelled. You also run the risk of getting a bad reputation among other users, who may not hesitate to spread the word about your bad behaviour.
Damaging your business's reputation
Breaking site rules is not the only way to damage your reputation. Using a 'hard sell' approach (even if it's strictly within the rules) will annoy other users and turn them off your business and product. Posting boring or unattractive photos will also undermine your marketing efforts. Every time you post a photo, consider carefully what it says about your business.