Putting the SWR concerns aside, if you are in a major metro area with a well engineered radio system, there's probably more than enough signal and overlap that a crappy antenna will still work fine.
You can tell if you radio system is well designed when the rubber ducky falls off a officers portable and he comes into the shop 3 weeks later saying "it still works ok, but I thought I would stop in...". If you are in a rural area or on a system that doesn't have "melting" coverage, then it may be a concern.
Sometimes the word comes down from a higher rank that doesn't know anything about radio to put the antenna where it is.
Besides the Sti-Co disguse antennas and bumper antennas, there's the good ole standby of the NMO phanton in the back window with a tissue box or trucker hat sitting on top of it.