Offers that reward creating an account, joining a mailing list, or referring a friend can provide real value, but they also ask for something in return that is easy to underweight: personal information, ongoing marketing contact, or a favor asked of someone else. Weighing that exchange properly means looking past the headline reward to what is actually being requested, rather than focusing only on the size of the discount or reward on offer.
A discount in exchange for an email address is a fairly low-cost trade for most shoppers, since an unwanted subscription can simply be unsubscribed from later. Offers that request a phone number, a full profile with personal details, or access to a social account carry a higher ongoing cost, since that information is harder to withdraw once shared and may be used well beyond the original offer. It is also worth checking whether the reward requires a first purchase to actually apply, since some sign-up discounts are only usable above a minimum order size.
Referral offers reward both the person referring and the person referred, which makes them different from most other offer types, since accepting one affects someone else's experience as well.
A useful test for any sign-up or referral offer is whether the reward would still feel worthwhile if the marketing contact or data sharing never stopped, since in practice it sometimes continues well past the point of the original transaction. Offers that ask for minimal, easily reversible information and provide a clear, immediate reward tend to hold up best under that test, while offers that ask for more than they give back are easier to decline without missing much. Reviewing account and email preferences every so often also makes it simple to keep only the sign-ups that are still delivering genuine value.