One phrase that can really trip up querying authors is usually near the end of the rejection/pass. It may say something like "Please think of me if you query future projects," "I hope you'll keep me in mind should you find yourself with a new manuscript to query," or "I'd love to see a query for your next project."
For the longest time I thought this was just something some agents put on their form rejections. AND THEN I LEARNED ABOUT TIERED FORMS. Essentially, just because it's a "form" rejection doesn't mean it's a sincere offer!
I cannot even begin to tell you how deeply I wish I'd learned this sooner. With my current querying project I mentioned an agent putting this in their last pass, and I got a full request that same day!
Not too much to say on this other than take note of anyone who uses this phrase in a pass and MENTION IT in the query letter of your next project when it's ready.