Costs of derivatives and manager fees make leveraged ETFs have a dangerous time decay. If trading for periods longer than a day, these kick in. How badly they impair performance depends on the of the underlyings, so be careful when trading these. A more clearly trending underlying makes for a safer leveraged play, so, instruments like QLD/QID aren't as affected by this.
You can observe how being short both sides of the coin, can produce a downtrend in the chart, and thus, a safe long term short.
Be careful when trading these for longer than a day, and if trading QLD , or QID , be careful with trades held for longer than a month, or a quarter (I estimate that is for how long they can outperform QQQ ).