When does the querying process become an act of desperation? For me I think it's five minutes after I finish my project. I get all panicky and freak out about writing a letter and synopsis that I break out into a sweat. It isn't until I get my first rejection that I calm down (sort of). Even then, I still find myself getting frustrated and depressed because I feel like no one will ever pick up my work and that I'm not good enough as a writer. It's at this stage that I become most vulnerable to scams and less-than-reputable agents/publishers. Luckily, I've never sent any money to any of these agencies or actually had them look at my manuscript, but it's bothersome that I fall into their trap. Is it really that important that I get my book published? Recently, I've come to the conclusion that no, it's not that important. I'm still young, I have plenty of time on my hands, and eventually someone somewhere will like my work. Some days are easier than others living with my new-found optimism, but I just try and keep myself busy.
By the way, I received two rejections in two days.