On one end of the spectrum are highly evangelical memes - which are good at using host resources to spread between hosts. Religions and causes tend to be evangelical.
At the other end are secretive memes - memes that the hosts mostly try to keep to themselves. For example, trade secrets are sometimes only socially transmitted between a highly select group of family members.
There's a spectrum of evangelism between these two extremes. There are memes that are paid for - for example in the form of mathematics tuition. There are copyrighted memes - which can be copied at the risk of punishment from the government.
Although there's a spectrum of evangelism, it has rather a binary flavour. At one end are memes whose hosts want to spread them. At the other are memes whose hosts want to keep them secret. These are secretive memes and evangelical memes respectively. Of course the memes themselves are not "secretive" - they are named after the class of behaviours they induce in their hosts.
Memes that are at an intermediate position on the evangelism spectrum often induce both evangelical and secretive behaviours in their hosts. For example, authors may simultaneously hawk their wares to consumers while sending DMCA takedown notices to pirates.
Secretive memes usually arise because of the value of information scarcity. When information in a domain is scarce, it becomes more valuable. For those that have it there is sometimes an incentive to not spread it around - in order to preserve its value.
Obviously, secretive memes face a serious disadvantage as a result of them lacking mechanisms for getting their hosts to spread them. One might wonder how they spread at all. However, usually the information they contain is valuable - so others are motivated to try and obtain it without the permission of its hosts. Industrial espionage is one way that trade secrets become liberated, for example. Also, hosts may sometimes pass the secrets on to trusted parties - so they are not lost when they die.