There is low, and then there is rubbish.
Some owners will start pretty low in a "start a trade conversation" kind of way which is OK.
These are the people that realize you can't insult someone's intelligence if you want to deal with them harmoniously in future.
Then there are the morons who offer waiver crud for your best players, and do it on a consistent basis. You clearly state what you like and don't like in the trade comments box and a week later the same crap is offered to you. These are the people who should be burned at the stake. We have one of those guys in one of my dynasty leagues, and it is actually possible to trade with him, but it is like pulling teeth.
So short answer - Only if it is on a consistent basis.
Solution: Post their offers on the league chat board, if they don't listen to you over a long period of time.