Where objections are lodged to a planning application, it is useful to bear in mind that the character (from a planning point of view) of the applicant is relevant.
Under Section 35 of the Planning and Development Act 2000 (as amended), the planning authority may form the opinion that the proposed development may not be completed in accordance with the requested permission or its conditions, and base a refusal of permission on that.
It will need evidence to form this opinion. The obvious evidence would be the previous conduct of the applicant in relation to developments.
Objectors, therefore should research the past history of an applicant and the history of his/her developments and provide that evidence to the planning authority.