It depends on a couple of things- how far along fermentation is, and how hot it actually got inside the fermenter during fermentation. If your room temperature is 78 degrees, and fermentation is in the first 36 hours, you could expect some fruity flavors and some "hot" alcohol taste. Maybe even solventy and band-aid like. Since fermentation is exothermic, the important temperature is the temperature of the beer and not the room temperature.
If the room temperature was 70 degrees, but it got up to 76 briefly in the fermenter before fermentation started (or after it ended), it would be much less likely to cause too many off-flavors. If there was fermentation during that hot period, you'd be much more likely to have off-flavors.