We recently learned the hard way that the use of haze can lead to reliability problems for some LCD projectors. We have two rather large LCD projectors (don’t know the specs offhand) permanently mounted to the ceiling, projecting onto the front of screens located on both sides of the stage. A third LCD projector hits a large rear-projection screen that basically forms the back wall of the stage. We also have an oil-based hazer mounted above the stage. We had some old, tired projectors, so we assumed that they were just old and unreliable. However, after replacing them with new, more powerful models, the reliability issues continued. After sending the new projectors out for service for the second time in less than a year, the service center informed us that a film of oil had been deposited on the LCD. You can buy expensive sealed-optics projectors, which should work reliably in dirty environments, but we saved money and bought standard models. We don’t have the budget to replace the “new” projectors, so we’ve had to stop using haze altogether. The stage doesn’t look nearly as good without it, and our moving lights are much less useful.
On a side note: you should be aware that haze can also damage moving light fixtures that use a fan to cool the power supply or motors. The fan sucks in haze and coats the internal components with a film of oil. Eventually, something overheats and the fixture can actually catch fire. Fortunately, we have older High End Studiospots and Trackspots that apparently don’t use forced-air cooling, so apparently the haze doesn’t really get inside. Be warned!