What do you mean glossy results? Wouldn't it be to your advantage to take down another researcher? Or do you mean they use null results to construct a better theory for more credit?

Glossy results are memeable stories that editors of journals would like to have in their next edition.

There is very little incentive in publicly criticising a paper, there is incentive to show why others are wrong and why your new technically superior method solves the problem and finds new insights to the field.