Myth #1 - Deacons are paid, they are on the parish payroll and will increase our costs.
In general, this is not true for approximately 80% of ordained deacons. Their diaconal assignments and ministry is volunteer, not renumerated by parish payroll. A Deacon may be employed by a Parish or a Diocese for a specific job opening, but that is separate from the diaconal service at Mass, Ministries that he leads or participates in which are not part of the job responsibilities that the deacon may be employed for.
In essence, if a Deacon is employed by a parish or diocese, he is renumerated for performing the duties and responsibilities of the position he is employed for. His diaconal service is in addition to his paid position, and he is not renumerated by either the parish or diocese for his diaconal service.
Myth #2 - Deacon's wives are also committed to service in the church since her husband is the deacon.
This is genuinely 100% not true. The wife of a deacon is not held to the same commitments as the deacon, as she is a different person and is not the one who was called to Holy Orders or ordained.
The Bishop, or priest at the parish where a deacon is assigned may ask the deacon and his wife to carry out a specific Mission as a couple - such as Marriage preparation, or parenting workshops/courses for parents and godparents in preparation for the baptism of children, etc.., but both the deacon and his wife would have to agree and freely consent to perform that specific ministry.
Myth #3 - Deacons are essentially "mini-priests"
This is a common myth or misunderstanding which is also 100% false. This myth or misunderstanding can be attributed to any number of sources of misinformation. It can also be attributed to 1). The history of the Diaconate in the life of the Church, 2). Not understanding the diaconate as a transitory step in formation for the priesthood, 3). A lack of understanding of who a Priest is vs who a Deacon is.
Myth #4 - Deacons are essentially "glorified altar servers"
This is also another common myth or misunderstanding which is also 100% false. In fact, Pope Francis has spoken out against having Deacons be used as little more than "glorified altar servers" as well as Deacons being "wannabe priests". The links below are to Pope Francis's writings or speeches on deacons in the Church.