That's quite a subtle issue! In principle, both parish and district councillors are restricted to comments that raise factors that are planning considerations. You're probably familiar with this. Some are quite general, such as planners do not decide whether a project is commercially viable or will affect local competition. Others are local, by virtue of the policies in place for the district. Comments that are not planning considerations should be disregarded when the decision is made.
But the reality is that decisions are made by human beings, and they may well be affected by any of the arguments that have been raised. This may apply more to councillors than officers. Clearly there need to be some planning considerations to support a refusal, or it will be easily overturned on appeal and incur costs for the planning authority. Or a perverse permission could be subject to judicial review. But if the considerations are at least somewhat balanced, there is scope to take account of local opinion and such like, even though this is not done overtly. Who knows exactly what determines a councillor's vote?