Innovations for carbon emission reduction require broad adoption, but initially attract a limited user base. Repeated surveys inform product and service adoption and discontinuance dynamics, yet statistical analyses may yield misleading results due to potentially overestimated question quality. Our examination of responses to a single question focusing on 16 low-carbon digital consumer innovations investigates their reliability in a 2019-2020 repeated survey. Notably, our investigation indicates that questions related to novel digital innovations, particularly services in contrast to physical products, tend to exhibit diminished reliability. Additionally, quantifying discontinuance presents greater challenges than measuring adoption. Therefore, results regarding the types of products or services adopted and discontinued may be affected by measurement error of responses. This study provides valuable insights for stakeholders interested in comprehending adoption and discontinuance dynamics through survey methodologies.