Sometimes they can be awesome other times shit, just depends on the quality of what you've been smoking beforehand. For example i smoke the oils reguarly from my bong after the grass has run out and it can get me high as fuck but the oils left by the dreaded soapbar (which due to some right bastard of circumstances i've had to smoke recently) make me feel groggy for 10 minutes then goes away. But one thing that is always the same regardless is the fact it tastes like shit, a good thing to do is take some kief from the grinder and put this on the oil and smoke it.