[mtlmtlmtlmtl]

Sugar is not poison or "clearly bad".

Sucrose is bad when eaten on its own, specifically in the abscence of fibre and other macronutrients that bring the GI down.

[mike10921]

It is not bad if one has self-control and eats a small amount of it, but that is really the case for most bad substances like alcohol, weed, etc.

If one is out of control eating sugar it is clearly going to have bad consequences. The immediate consequences will be obesity and bad teeth. The long-term would be diabetes, and there are definitely others as well.