This paper analyzes the findings of a set of field studies that explored the use of near field communication (NFC) tags in a mixed reality environment for providing access to digital services by touching a tag with a mobile phone. The field studies provide insight into user experience, usability, user acceptance and technical implementation issues that need to be considered when designing tag-based services. The paper proposes that if NFC technology becomes common, there is a compelling need for methods and practices for tag management. If such practices are not used and available, tags can form "tag litter" that ruins the user experience by corrupting the trust towards tags and tag-based services.