The phrase "iffy proposition" means that something is uncertain or risky. It suggests that there is a good chance of it not working out or being successful. Full definition
Signings in bookstores can be iffy propositions because you are depending on customers, whose reading tastes are varied, to be interested in your book. (behlerblog.com)
Over a longer period than just the first month, I believe stocks are still an iffy proposition for 2012. (canadianbusiness.com)
Tournament purses were meager and finding a good baby - sitter was an iffy proposition. (si.com)