It is not sticky situation. I think that It had been sticky for those people who have played that game. All are awe about it option. When I have played it first time I have also faced that issue But When I have surveyed more then I have found it very well and enjoyed the game.
The trick to this level is towards the end. Here is one way to get through it with a decent score:
1)Get a set-up by level 39 like pictured in the 1st attached pic (There is only one boomerang- full power)
2)Use the Spider when you have 5 creeps left on level 39. Don't slow the creeps with the spider just move him under the door. You will have just enough juice left to slow the boss in level 40 (Again don't slow the creeps...just wait until the boss comes and slow him down).
3)Use the spider on level 45 AS SOON AS YOU CAN. Don't wait at all.
4)On level 48, your set-up should look like the 2nd attached picture. Don't add anything before level 48! You need to drag each level out as long as possible so the spider has more time to charge.
5)By level 50, your spider should juice up when the boss is mid way through giving you plenty of time to defeat him.
On all levels, make sure you hand target any fast moving creeps and kill them 1st. And of course sell everything before the level ends to maximize your cash bonus and your score. And now you have your gold star.
Hope this helps
This helped quite a bit, although there was no way I could use the spider on levels 40, 45 AND 50, despite following instructions to the letter. I had to find a way to beat level 40 without using the spider, and I did so by temporarily adding a fully-upgraded laser. I then sold it until following step 4 above, so that the spider had time to recharge between level 45 and 50. After a RIDICULOUS number of attempts, I finally got perfect on this level.