Every tool can be misapplied or misused.

If the 'dogs' can provide a scientifically credible means for 'flagging' that's significantly above random chance, but still below the threshold 'beyond a shadow of a doubt' they can absolutely be used.

If a police officer smells the odor of marijuana in the car, or alcohol on the breath, or, for example, sees a crack pipe or 'empty beer' cans - those things are all examples of reasonable suspicion and it's the whole point.

That those powers can be abused is again a secondary issue.

Finally, is the obvious issue that there's very little harm done otherwise, the 'false flags' from either dogs or 'empty beer' cans that result in searching doesn't compromise the individuals or the community at large: a 'blow test' or a 'legal search' results in more accurate presentation of justice, not less.

That's the problem. They cannot.

" narcotics-detecting dogs and their handlers aren’t very good at discerning the presence of illegal drugs. Multiple analyses of drug-dog alerts have consistently shown alarmingly high error rates — with some close to and exceeding 50 percent. In effect, some of these K-9 units are worse than a coin flip." https://www.washingtonpost.com/opinions/2019/02/05/supreme-c...