Steps to reproduce:

1. Create item with Type of information set to Character, Text or Log. 
2. Open Graphs page in the web interface of the host with that item. 

/zabbix.php?action=charts.view 

Result:
Empty simple graph gets displayed for items with no graphable data. Furthermore you can disable History and Trends collection from item altogether (for dependent item preprocessing purposes) thus "History" links are no more available in e.g. Latest data page, yet still Simple graphs exist. 

This gets extremely confusing when building a visualization for larger number of host based entities where general Dashboards will not be good because of too many manually created objects (plus can't be exported as templates), and template dashboards are also made useless for LLD objects because of pagination as reported in ZBX-20997 . Graphs page was the last hope but that has to do the extra step of clicking "Host graphs" and may not be always straightforward for all users. 

Expected:
No Graphs for text items.