If you have an opinion that something is bad and you wish to express it,
it is better to avoid using negative labels like stupid and suck.

Negative labels either potentially hurt other people’s feelings
or it will fill your mind with negativity (yuck!)
so cut down or simply avoid the usage of negative labels.

You can use positive and constructive labels as alternative.
Here’s a suggestion :

instead of saying something sucks or someone is stupid,
use labels like

“(s)he has a lot of room for improvement”

“it can be done better”