Normally the officer needs to make a positive association between the paraphernalia (or drugs) and one of the suspects. That happens if one suspect has the items in question on his person or if one suspect admits "Yeah, the stuff is mine." If no one owns up to possessing the paraphernalia, he'll cite everyone involved.

Doesn't sound like your former girlfriend owned up to the pipes being hers. Doesn't sound like you did too good a job of proving your distance from them or the rental situation, either. When an officer begins putting words in your mouth like that, you need to courteously stop him, correct him with the truth, and be able to back up what you're saying. If you have lease paperwork, rental payment receipts, copies of her receipts for those pipes, some concrete proof that you were a short-timer there and that they're hers, go to court with those and prove your innocence.

If not--and I gather this is the hitch in this case--then you're both going to have to pony up the fine for that citation. Consider it a relatively easy lesson learned. Seriously, she could have had a pound of brick weed and a baggie full of white powder on that coffee table and pretended like they weren't remotely associated with her. A misdemeanor citation for a couple of pipes is a fairly benign offense. Next time you request a public assist from a police officer, make sure the coast is clear before he assists you so that you're taking responsibility for your protection.