i recently bought some plastic weld, the back label says methylene chloride, but does not say if theres any other ingredients. i tried doing a caffeine extraction and it just smelled off.... so im wondering, what are the chances its clean?

its E.M.A model supplies plastic weld

I doubt it will be any good for extracting dmt. Have you tried to evaporate some of the glue to see if it does evaporate? I'm guessing it won't.

I just seen this is DCM. I'm not sure at all about this stuff as ive never used it.

Don't use hobby glue or anything. Get some proper pure solvent from a local DIY shop. Almost all DIY shops sell naphtha without any additives. And those bottles will also have a MSDS chart number so you can check to be 100% sure.

If you don't have a list of ingredients, assume it's not pure.

A glue is a glue exactly because there is an adhesive that stays behind once the solvent evaporates, you cant use that as a solvent.