Took 150mg xr wellbutrin (bupropion) for 30 days with no noticeable effects, except dry mouth. stopped altogether with no change. safe to say it was a waste?

Not a waste: The experience of having no response to bupropion (or perhaps any med) rules out the usefulness of that medication which is helpful to note for future reference. However, one can be a "high or rapid metabolizer" of certain meds which may then require higher doses (I had a patient once who had to take 500mg Sertraline to get her serum levels to therapeutic values). A switch to another med may help.

Wellbutrin (bupropion): Nope. You did not reach the therapeutic dose to see full effectiveness (300-450mg.). Talk to your doctor before stopping any medication.

Target symptoms: You mention no noticeable effects, and I assume you mean side effects, and not target symptoms for which WBT was prescribed. If there was no change after you stopped, i could agree to this med not useful for you.

No.: The dose was insufficient to decide that there will be no therapeutic benefit. ON the other hand, the dry mouth might get worse if the dose is raised.